INSTRUCTION
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Trains a k-nearest neighbors classifier for face recognition.
:param train_dir: directory that contains a sub-directory for each known person, with its name.
(View in source code to see train_dir example tree structure)
Structure:
<train_dir>/
├── <person1>/
│ ├── <somename1>.jpeg
│ ├── <somename2>.jpeg
│ ├── ...
├── <person2>/
│ ├── <somename1>.jpeg
│ └── <somename2>.jpeg
└── ...
:param model_save_path: (optional) path to save model on disk
:param n_neighbors: (optional) number of neighbors to weigh in classification. Chosen automatically if not specified
:param knn_algo: (optional) underlying data structure to support knn.default is ball_tree
:param verbose: verbosity of training
:return: returns knn classifier that was trained on the given data. | def train(train_dir, model_save_path=None, n_neighbors=None, knn_algo='ball_tree', verbose=False):
"""
Trains a k-nearest neighbors classifier for face recognition.
:param train_dir: directory that contains a sub-directory for each known person, with its name.
(View in source code to see train_dir example tree structure)
Structure:
<train_dir>/
├── <person1>/
│ ├── <somename1>.jpeg
│ ├── <somename2>.jpeg
│ ├── ...
├── <person2>/
│ ├── <somename1>.jpeg
│ └── <somename2>.jpeg
└── ...
:param model_save_path: (optional) path to save model on disk
:param n_neighbors: (optional) number of neighbors to weigh in classification. Chosen automatically if not specified
:param knn_algo: (optional) underlying data structure to support knn.default is ball_tree
:param verbose: verbosity of training
:return: returns knn classifier that was trained on the given data.
"""
X = []
y = []
# Loop through each person in the training set
for class_dir in os.listdir(train_dir):
if not os.path.isdir(os.path.join(train_dir, class_dir)):
continue
# Loop through each training image for the current person
for img_path in image_files_in_folder(os.path.join(train_dir, class_dir)):
image = face_recognition.load_image_file(img_path)
face_bounding_boxes = face_recognition.face_locations(image)
if len(face_bounding_boxes) != 1:
# If there are no people (or too many people) in a training image, skip the image.
if verbose:
print("Image {} not suitable for training: {}".format(img_path, "Didn't find a face" if len(face_bounding_boxes) < 1 else "Found more than one face"))
else:
# Add face encoding for current image to the training set
X.append(face_recognition.face_encodings(image, known_face_locations=face_bounding_boxes)[0])
y.append(class_dir)
# Determine how many neighbors to use for weighting in the KNN classifier
if n_neighbors is None:
n_neighbors = int(round(math.sqrt(len(X))))
if verbose:
print("Chose n_neighbors automatically:", n_neighbors)
# Create and train the KNN classifier
knn_clf = neighbors.KNeighborsClassifier(n_neighbors=n_neighbors, algorithm=knn_algo, weights='distance')
knn_clf.fit(X, y)
# Save the trained KNN classifier
if model_save_path is not None:
with open(model_save_path, 'wb') as f:
pickle.dump(knn_clf, f)
return knn_clf |
Recognizes faces in given image using a trained KNN classifier
:param X_img_path: path to image to be recognized
:param knn_clf: (optional) a knn classifier object. if not specified, model_save_path must be specified.
:param model_path: (optional) path to a pickled knn classifier. if not specified, model_save_path must be knn_clf.
:param distance_threshold: (optional) distance threshold for face classification. the larger it is, the more chance
of mis-classifying an unknown person as a known one.
:return: a list of names and face locations for the recognized faces in the image: [(name, bounding box), ...].
For faces of unrecognized persons, the name 'unknown' will be returned. | def predict(X_img_path, knn_clf=None, model_path=None, distance_threshold=0.6):
"""
Recognizes faces in given image using a trained KNN classifier
:param X_img_path: path to image to be recognized
:param knn_clf: (optional) a knn classifier object. if not specified, model_save_path must be specified.
:param model_path: (optional) path to a pickled knn classifier. if not specified, model_save_path must be knn_clf.
:param distance_threshold: (optional) distance threshold for face classification. the larger it is, the more chance
of mis-classifying an unknown person as a known one.
:return: a list of names and face locations for the recognized faces in the image: [(name, bounding box), ...].
For faces of unrecognized persons, the name 'unknown' will be returned.
"""
if not os.path.isfile(X_img_path) or os.path.splitext(X_img_path)[1][1:] not in ALLOWED_EXTENSIONS:
raise Exception("Invalid image path: {}".format(X_img_path))
if knn_clf is None and model_path is None:
raise Exception("Must supply knn classifier either thourgh knn_clf or model_path")
# Load a trained KNN model (if one was passed in)
if knn_clf is None:
with open(model_path, 'rb') as f:
knn_clf = pickle.load(f)
# Load image file and find face locations
X_img = face_recognition.load_image_file(X_img_path)
X_face_locations = face_recognition.face_locations(X_img)
# If no faces are found in the image, return an empty result.
if len(X_face_locations) == 0:
return []
# Find encodings for faces in the test iamge
faces_encodings = face_recognition.face_encodings(X_img, known_face_locations=X_face_locations)
# Use the KNN model to find the best matches for the test face
closest_distances = knn_clf.kneighbors(faces_encodings, n_neighbors=1)
are_matches = [closest_distances[0][i][0] <= distance_threshold for i in range(len(X_face_locations))]
# Predict classes and remove classifications that aren't within the threshold
return [(pred, loc) if rec else ("unknown", loc) for pred, loc, rec in zip(knn_clf.predict(faces_encodings), X_face_locations, are_matches)] |
Shows the face recognition results visually.
:param img_path: path to image to be recognized
:param predictions: results of the predict function
:return: | def show_prediction_labels_on_image(img_path, predictions):
"""
Shows the face recognition results visually.
:param img_path: path to image to be recognized
:param predictions: results of the predict function
:return:
"""
pil_image = Image.open(img_path).convert("RGB")
draw = ImageDraw.Draw(pil_image)
for name, (top, right, bottom, left) in predictions:
# Draw a box around the face using the Pillow module
draw.rectangle(((left, top), (right, bottom)), outline=(0, 0, 255))
# There's a bug in Pillow where it blows up with non-UTF-8 text
# when using the default bitmap font
name = name.encode("UTF-8")
# Draw a label with a name below the face
text_width, text_height = draw.textsize(name)
draw.rectangle(((left, bottom - text_height - 10), (right, bottom)), fill=(0, 0, 255), outline=(0, 0, 255))
draw.text((left + 6, bottom - text_height - 5), name, fill=(255, 255, 255, 255))
# Remove the drawing library from memory as per the Pillow docs
del draw
# Display the resulting image
pil_image.show() |
Convert a dlib 'rect' object to a plain tuple in (top, right, bottom, left) order
:param rect: a dlib 'rect' object
:return: a plain tuple representation of the rect in (top, right, bottom, left) order | def _rect_to_css(rect):
"""
Convert a dlib 'rect' object to a plain tuple in (top, right, bottom, left) order
:param rect: a dlib 'rect' object
:return: a plain tuple representation of the rect in (top, right, bottom, left) order
"""
return rect.top(), rect.right(), rect.bottom(), rect.left() |
Make sure a tuple in (top, right, bottom, left) order is within the bounds of the image.
:param css: plain tuple representation of the rect in (top, right, bottom, left) order
:param image_shape: numpy shape of the image array
:return: a trimmed plain tuple representation of the rect in (top, right, bottom, left) order | def _trim_css_to_bounds(css, image_shape):
"""
Make sure a tuple in (top, right, bottom, left) order is within the bounds of the image.
:param css: plain tuple representation of the rect in (top, right, bottom, left) order
:param image_shape: numpy shape of the image array
:return: a trimmed plain tuple representation of the rect in (top, right, bottom, left) order
"""
return max(css[0], 0), min(css[1], image_shape[1]), min(css[2], image_shape[0]), max(css[3], 0) |
Given a list of face encodings, compare them to a known face encoding and get a euclidean distance
for each comparison face. The distance tells you how similar the faces are.
:param faces: List of face encodings to compare
:param face_to_compare: A face encoding to compare against
:return: A numpy ndarray with the distance for each face in the same order as the 'faces' array | def face_distance(face_encodings, face_to_compare):
"""
Given a list of face encodings, compare them to a known face encoding and get a euclidean distance
for each comparison face. The distance tells you how similar the faces are.
:param faces: List of face encodings to compare
:param face_to_compare: A face encoding to compare against
:return: A numpy ndarray with the distance for each face in the same order as the 'faces' array
"""
if len(face_encodings) == 0:
return np.empty((0))
return np.linalg.norm(face_encodings - face_to_compare, axis=1) |
Loads an image file (.jpg, .png, etc) into a numpy array
:param file: image file name or file object to load
:param mode: format to convert the image to. Only 'RGB' (8-bit RGB, 3 channels) and 'L' (black and white) are supported.
:return: image contents as numpy array | def load_image_file(file, mode='RGB'):
"""
Loads an image file (.jpg, .png, etc) into a numpy array
:param file: image file name or file object to load
:param mode: format to convert the image to. Only 'RGB' (8-bit RGB, 3 channels) and 'L' (black and white) are supported.
:return: image contents as numpy array
"""
im = PIL.Image.open(file)
if mode:
im = im.convert(mode)
return np.array(im) |
Returns an array of bounding boxes of human faces in a image
:param img: An image (as a numpy array)
:param number_of_times_to_upsample: How many times to upsample the image looking for faces. Higher numbers find smaller faces.
:param model: Which face detection model to use. "hog" is less accurate but faster on CPUs. "cnn" is a more accurate
deep-learning model which is GPU/CUDA accelerated (if available). The default is "hog".
:return: A list of dlib 'rect' objects of found face locations | def _raw_face_locations(img, number_of_times_to_upsample=1, model="hog"):
"""
Returns an array of bounding boxes of human faces in a image
:param img: An image (as a numpy array)
:param number_of_times_to_upsample: How many times to upsample the image looking for faces. Higher numbers find smaller faces.
:param model: Which face detection model to use. "hog" is less accurate but faster on CPUs. "cnn" is a more accurate
deep-learning model which is GPU/CUDA accelerated (if available). The default is "hog".
:return: A list of dlib 'rect' objects of found face locations
"""
if model == "cnn":
return cnn_face_detector(img, number_of_times_to_upsample)
else:
return face_detector(img, number_of_times_to_upsample) |
Returns an array of bounding boxes of human faces in a image
:param img: An image (as a numpy array)
:param number_of_times_to_upsample: How many times to upsample the image looking for faces. Higher numbers find smaller faces.
:param model: Which face detection model to use. "hog" is less accurate but faster on CPUs. "cnn" is a more accurate
deep-learning model which is GPU/CUDA accelerated (if available). The default is "hog".
:return: A list of tuples of found face locations in css (top, right, bottom, left) order | def face_locations(img, number_of_times_to_upsample=1, model="hog"):
"""
Returns an array of bounding boxes of human faces in a image
:param img: An image (as a numpy array)
:param number_of_times_to_upsample: How many times to upsample the image looking for faces. Higher numbers find smaller faces.
:param model: Which face detection model to use. "hog" is less accurate but faster on CPUs. "cnn" is a more accurate
deep-learning model which is GPU/CUDA accelerated (if available). The default is "hog".
:return: A list of tuples of found face locations in css (top, right, bottom, left) order
"""
if model == "cnn":
return [_trim_css_to_bounds(_rect_to_css(face.rect), img.shape) for face in _raw_face_locations(img, number_of_times_to_upsample, "cnn")]
else:
return [_trim_css_to_bounds(_rect_to_css(face), img.shape) for face in _raw_face_locations(img, number_of_times_to_upsample, model)] |
Returns an 2d array of bounding boxes of human faces in a image using the cnn face detector
If you are using a GPU, this can give you much faster results since the GPU
can process batches of images at once. If you aren't using a GPU, you don't need this function.
:param img: A list of images (each as a numpy array)
:param number_of_times_to_upsample: How many times to upsample the image looking for faces. Higher numbers find smaller faces.
:param batch_size: How many images to include in each GPU processing batch.
:return: A list of tuples of found face locations in css (top, right, bottom, left) order | def batch_face_locations(images, number_of_times_to_upsample=1, batch_size=128):
"""
Returns an 2d array of bounding boxes of human faces in a image using the cnn face detector
If you are using a GPU, this can give you much faster results since the GPU
can process batches of images at once. If you aren't using a GPU, you don't need this function.
:param img: A list of images (each as a numpy array)
:param number_of_times_to_upsample: How many times to upsample the image looking for faces. Higher numbers find smaller faces.
:param batch_size: How many images to include in each GPU processing batch.
:return: A list of tuples of found face locations in css (top, right, bottom, left) order
"""
def convert_cnn_detections_to_css(detections):
return [_trim_css_to_bounds(_rect_to_css(face.rect), images[0].shape) for face in detections]
raw_detections_batched = _raw_face_locations_batched(images, number_of_times_to_upsample, batch_size)
return list(map(convert_cnn_detections_to_css, raw_detections_batched)) |
Given an image, returns a dict of face feature locations (eyes, nose, etc) for each face in the image
:param face_image: image to search
:param face_locations: Optionally provide a list of face locations to check.
:param model: Optional - which model to use. "large" (default) or "small" which only returns 5 points but is faster.
:return: A list of dicts of face feature locations (eyes, nose, etc) | def face_landmarks(face_image, face_locations=None, model="large"):
"""
Given an image, returns a dict of face feature locations (eyes, nose, etc) for each face in the image
:param face_image: image to search
:param face_locations: Optionally provide a list of face locations to check.
:param model: Optional - which model to use. "large" (default) or "small" which only returns 5 points but is faster.
:return: A list of dicts of face feature locations (eyes, nose, etc)
"""
landmarks = _raw_face_landmarks(face_image, face_locations, model)
landmarks_as_tuples = [[(p.x, p.y) for p in landmark.parts()] for landmark in landmarks]
# For a definition of each point index, see https://cdn-images-1.medium.com/max/1600/1*AbEg31EgkbXSQehuNJBlWg.png
if model == 'large':
return [{
"chin": points[0:17],
"left_eyebrow": points[17:22],
"right_eyebrow": points[22:27],
"nose_bridge": points[27:31],
"nose_tip": points[31:36],
"left_eye": points[36:42],
"right_eye": points[42:48],
"top_lip": points[48:55] + [points[64]] + [points[63]] + [points[62]] + [points[61]] + [points[60]],
"bottom_lip": points[54:60] + [points[48]] + [points[60]] + [points[67]] + [points[66]] + [points[65]] + [points[64]]
} for points in landmarks_as_tuples]
elif model == 'small':
return [{
"nose_tip": [points[4]],
"left_eye": points[2:4],
"right_eye": points[0:2],
} for points in landmarks_as_tuples]
else:
raise ValueError("Invalid landmarks model type. Supported models are ['small', 'large'].") |
Given an image, return the 128-dimension face encoding for each face in the image.
:param face_image: The image that contains one or more faces
:param known_face_locations: Optional - the bounding boxes of each face if you already know them.
:param num_jitters: How many times to re-sample the face when calculating encoding. Higher is more accurate, but slower (i.e. 100 is 100x slower)
:return: A list of 128-dimensional face encodings (one for each face in the image) | def face_encodings(face_image, known_face_locations=None, num_jitters=1):
"""
Given an image, return the 128-dimension face encoding for each face in the image.
:param face_image: The image that contains one or more faces
:param known_face_locations: Optional - the bounding boxes of each face if you already know them.
:param num_jitters: How many times to re-sample the face when calculating encoding. Higher is more accurate, but slower (i.e. 100 is 100x slower)
:return: A list of 128-dimensional face encodings (one for each face in the image)
"""
raw_landmarks = _raw_face_landmarks(face_image, known_face_locations, model="small")
return [np.array(face_encoder.compute_face_descriptor(face_image, raw_landmark_set, num_jitters)) for raw_landmark_set in raw_landmarks] |
Parses the given data type string to a :class:`DataType`. The data type string format equals
to :class:`DataType.simpleString`, except that top level struct type can omit
the ``struct<>`` and atomic types use ``typeName()`` as their format, e.g. use ``byte`` instead
of ``tinyint`` for :class:`ByteType`. We can also use ``int`` as a short name
for :class:`IntegerType`. Since Spark 2.3, this also supports a schema in a DDL-formatted
string and case-insensitive strings.
>>> _parse_datatype_string("int ")
IntegerType
>>> _parse_datatype_string("INT ")
IntegerType
>>> _parse_datatype_string("a: byte, b: decimal( 16 , 8 ) ")
StructType(List(StructField(a,ByteType,true),StructField(b,DecimalType(16,8),true)))
>>> _parse_datatype_string("a DOUBLE, b STRING")
StructType(List(StructField(a,DoubleType,true),StructField(b,StringType,true)))
>>> _parse_datatype_string("a: array< short>")
StructType(List(StructField(a,ArrayType(ShortType,true),true)))
>>> _parse_datatype_string(" map<string , string > ")
MapType(StringType,StringType,true)
>>> # Error cases
>>> _parse_datatype_string("blabla") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
>>> _parse_datatype_string("a: int,") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
>>> _parse_datatype_string("array<int") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
>>> _parse_datatype_string("map<int, boolean>>") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:... | def _parse_datatype_string(s):
"""
Parses the given data type string to a :class:`DataType`. The data type string format equals
to :class:`DataType.simpleString`, except that top level struct type can omit
the ``struct<>`` and atomic types use ``typeName()`` as their format, e.g. use ``byte`` instead
of ``tinyint`` for :class:`ByteType`. We can also use ``int`` as a short name
for :class:`IntegerType`. Since Spark 2.3, this also supports a schema in a DDL-formatted
string and case-insensitive strings.
>>> _parse_datatype_string("int ")
IntegerType
>>> _parse_datatype_string("INT ")
IntegerType
>>> _parse_datatype_string("a: byte, b: decimal( 16 , 8 ) ")
StructType(List(StructField(a,ByteType,true),StructField(b,DecimalType(16,8),true)))
>>> _parse_datatype_string("a DOUBLE, b STRING")
StructType(List(StructField(a,DoubleType,true),StructField(b,StringType,true)))
>>> _parse_datatype_string("a: array< short>")
StructType(List(StructField(a,ArrayType(ShortType,true),true)))
>>> _parse_datatype_string(" map<string , string > ")
MapType(StringType,StringType,true)
>>> # Error cases
>>> _parse_datatype_string("blabla") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
>>> _parse_datatype_string("a: int,") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
>>> _parse_datatype_string("array<int") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
>>> _parse_datatype_string("map<int, boolean>>") # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ParseException:...
"""
sc = SparkContext._active_spark_context
def from_ddl_schema(type_str):
return _parse_datatype_json_string(
sc._jvm.org.apache.spark.sql.types.StructType.fromDDL(type_str).json())
def from_ddl_datatype(type_str):
return _parse_datatype_json_string(
sc._jvm.org.apache.spark.sql.api.python.PythonSQLUtils.parseDataType(type_str).json())
try:
# DDL format, "fieldname datatype, fieldname datatype".
return from_ddl_schema(s)
except Exception as e:
try:
# For backwards compatibility, "integer", "struct<fieldname: datatype>" and etc.
return from_ddl_datatype(s)
except:
try:
# For backwards compatibility, "fieldname: datatype, fieldname: datatype" case.
return from_ddl_datatype("struct<%s>" % s.strip())
except:
raise e |
Return the Catalyst datatype from the size of integers. | def _int_size_to_type(size):
"""
Return the Catalyst datatype from the size of integers.
"""
if size <= 8:
return ByteType
if size <= 16:
return ShortType
if size <= 32:
return IntegerType
if size <= 64:
return LongType |
Infer the DataType from obj | def _infer_type(obj):
"""Infer the DataType from obj
"""
if obj is None:
return NullType()
if hasattr(obj, '__UDT__'):
return obj.__UDT__
dataType = _type_mappings.get(type(obj))
if dataType is DecimalType:
# the precision and scale of `obj` may be different from row to row.
return DecimalType(38, 18)
elif dataType is not None:
return dataType()
if isinstance(obj, dict):
for key, value in obj.items():
if key is not None and value is not None:
return MapType(_infer_type(key), _infer_type(value), True)
return MapType(NullType(), NullType(), True)
elif isinstance(obj, list):
for v in obj:
if v is not None:
return ArrayType(_infer_type(obj[0]), True)
return ArrayType(NullType(), True)
elif isinstance(obj, array):
if obj.typecode in _array_type_mappings:
return ArrayType(_array_type_mappings[obj.typecode](), False)
else:
raise TypeError("not supported type: array(%s)" % obj.typecode)
else:
try:
return _infer_schema(obj)
except TypeError:
raise TypeError("not supported type: %s" % type(obj)) |
Infer the schema from dict/namedtuple/object | def _infer_schema(row, names=None):
"""Infer the schema from dict/namedtuple/object"""
if isinstance(row, dict):
items = sorted(row.items())
elif isinstance(row, (tuple, list)):
if hasattr(row, "__fields__"): # Row
items = zip(row.__fields__, tuple(row))
elif hasattr(row, "_fields"): # namedtuple
items = zip(row._fields, tuple(row))
else:
if names is None:
names = ['_%d' % i for i in range(1, len(row) + 1)]
elif len(names) < len(row):
names.extend('_%d' % i for i in range(len(names) + 1, len(row) + 1))
items = zip(names, row)
elif hasattr(row, "__dict__"): # object
items = sorted(row.__dict__.items())
else:
raise TypeError("Can not infer schema for type: %s" % type(row))
fields = [StructField(k, _infer_type(v), True) for k, v in items]
return StructType(fields) |
Return whether there is NullType in `dt` or not | def _has_nulltype(dt):
""" Return whether there is NullType in `dt` or not """
if isinstance(dt, StructType):
return any(_has_nulltype(f.dataType) for f in dt.fields)
elif isinstance(dt, ArrayType):
return _has_nulltype((dt.elementType))
elif isinstance(dt, MapType):
return _has_nulltype(dt.keyType) or _has_nulltype(dt.valueType)
else:
return isinstance(dt, NullType) |
Create a converter to drop the names of fields in obj | def _create_converter(dataType):
"""Create a converter to drop the names of fields in obj """
if not _need_converter(dataType):
return lambda x: x
if isinstance(dataType, ArrayType):
conv = _create_converter(dataType.elementType)
return lambda row: [conv(v) for v in row]
elif isinstance(dataType, MapType):
kconv = _create_converter(dataType.keyType)
vconv = _create_converter(dataType.valueType)
return lambda row: dict((kconv(k), vconv(v)) for k, v in row.items())
elif isinstance(dataType, NullType):
return lambda x: None
elif not isinstance(dataType, StructType):
return lambda x: x
# dataType must be StructType
names = [f.name for f in dataType.fields]
converters = [_create_converter(f.dataType) for f in dataType.fields]
convert_fields = any(_need_converter(f.dataType) for f in dataType.fields)
def convert_struct(obj):
if obj is None:
return
if isinstance(obj, (tuple, list)):
if convert_fields:
return tuple(conv(v) for v, conv in zip(obj, converters))
else:
return tuple(obj)
if isinstance(obj, dict):
d = obj
elif hasattr(obj, "__dict__"): # object
d = obj.__dict__
else:
raise TypeError("Unexpected obj type: %s" % type(obj))
if convert_fields:
return tuple([conv(d.get(name)) for name, conv in zip(names, converters)])
else:
return tuple([d.get(name) for name in names])
return convert_struct |
Make a verifier that checks the type of obj against dataType and raises a TypeError if they do
not match.
This verifier also checks the value of obj against datatype and raises a ValueError if it's not
within the allowed range, e.g. using 128 as ByteType will overflow. Note that, Python float is
not checked, so it will become infinity when cast to Java float if it overflows.
>>> _make_type_verifier(StructType([]))(None)
>>> _make_type_verifier(StringType())("")
>>> _make_type_verifier(LongType())(0)
>>> _make_type_verifier(ArrayType(ShortType()))(list(range(3)))
>>> _make_type_verifier(ArrayType(StringType()))(set()) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
TypeError:...
>>> _make_type_verifier(MapType(StringType(), IntegerType()))({})
>>> _make_type_verifier(StructType([]))(())
>>> _make_type_verifier(StructType([]))([])
>>> _make_type_verifier(StructType([]))([1]) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> # Check if numeric values are within the allowed range.
>>> _make_type_verifier(ByteType())(12)
>>> _make_type_verifier(ByteType())(1234) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> _make_type_verifier(ByteType(), False)(None) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> _make_type_verifier(
... ArrayType(ShortType(), False))([1, None]) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> _make_type_verifier(MapType(StringType(), IntegerType()))({None: 1})
Traceback (most recent call last):
...
ValueError:...
>>> schema = StructType().add("a", IntegerType()).add("b", StringType(), False)
>>> _make_type_verifier(schema)((1, None)) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:... | def _make_type_verifier(dataType, nullable=True, name=None):
"""
Make a verifier that checks the type of obj against dataType and raises a TypeError if they do
not match.
This verifier also checks the value of obj against datatype and raises a ValueError if it's not
within the allowed range, e.g. using 128 as ByteType will overflow. Note that, Python float is
not checked, so it will become infinity when cast to Java float if it overflows.
>>> _make_type_verifier(StructType([]))(None)
>>> _make_type_verifier(StringType())("")
>>> _make_type_verifier(LongType())(0)
>>> _make_type_verifier(ArrayType(ShortType()))(list(range(3)))
>>> _make_type_verifier(ArrayType(StringType()))(set()) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
TypeError:...
>>> _make_type_verifier(MapType(StringType(), IntegerType()))({})
>>> _make_type_verifier(StructType([]))(())
>>> _make_type_verifier(StructType([]))([])
>>> _make_type_verifier(StructType([]))([1]) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> # Check if numeric values are within the allowed range.
>>> _make_type_verifier(ByteType())(12)
>>> _make_type_verifier(ByteType())(1234) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> _make_type_verifier(ByteType(), False)(None) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> _make_type_verifier(
... ArrayType(ShortType(), False))([1, None]) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
>>> _make_type_verifier(MapType(StringType(), IntegerType()))({None: 1})
Traceback (most recent call last):
...
ValueError:...
>>> schema = StructType().add("a", IntegerType()).add("b", StringType(), False)
>>> _make_type_verifier(schema)((1, None)) # doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
ValueError:...
"""
if name is None:
new_msg = lambda msg: msg
new_name = lambda n: "field %s" % n
else:
new_msg = lambda msg: "%s: %s" % (name, msg)
new_name = lambda n: "field %s in %s" % (n, name)
def verify_nullability(obj):
if obj is None:
if nullable:
return True
else:
raise ValueError(new_msg("This field is not nullable, but got None"))
else:
return False
_type = type(dataType)
def assert_acceptable_types(obj):
assert _type in _acceptable_types, \
new_msg("unknown datatype: %s for object %r" % (dataType, obj))
def verify_acceptable_types(obj):
# subclass of them can not be fromInternal in JVM
if type(obj) not in _acceptable_types[_type]:
raise TypeError(new_msg("%s can not accept object %r in type %s"
% (dataType, obj, type(obj))))
if isinstance(dataType, StringType):
# StringType can work with any types
verify_value = lambda _: _
elif isinstance(dataType, UserDefinedType):
verifier = _make_type_verifier(dataType.sqlType(), name=name)
def verify_udf(obj):
if not (hasattr(obj, '__UDT__') and obj.__UDT__ == dataType):
raise ValueError(new_msg("%r is not an instance of type %r" % (obj, dataType)))
verifier(dataType.toInternal(obj))
verify_value = verify_udf
elif isinstance(dataType, ByteType):
def verify_byte(obj):
assert_acceptable_types(obj)
verify_acceptable_types(obj)
if obj < -128 or obj > 127:
raise ValueError(new_msg("object of ByteType out of range, got: %s" % obj))
verify_value = verify_byte
elif isinstance(dataType, ShortType):
def verify_short(obj):
assert_acceptable_types(obj)
verify_acceptable_types(obj)
if obj < -32768 or obj > 32767:
raise ValueError(new_msg("object of ShortType out of range, got: %s" % obj))
verify_value = verify_short
elif isinstance(dataType, IntegerType):
def verify_integer(obj):
assert_acceptable_types(obj)
verify_acceptable_types(obj)
if obj < -2147483648 or obj > 2147483647:
raise ValueError(
new_msg("object of IntegerType out of range, got: %s" % obj))
verify_value = verify_integer
elif isinstance(dataType, ArrayType):
element_verifier = _make_type_verifier(
dataType.elementType, dataType.containsNull, name="element in array %s" % name)
def verify_array(obj):
assert_acceptable_types(obj)
verify_acceptable_types(obj)
for i in obj:
element_verifier(i)
verify_value = verify_array
elif isinstance(dataType, MapType):
key_verifier = _make_type_verifier(dataType.keyType, False, name="key of map %s" % name)
value_verifier = _make_type_verifier(
dataType.valueType, dataType.valueContainsNull, name="value of map %s" % name)
def verify_map(obj):
assert_acceptable_types(obj)
verify_acceptable_types(obj)
for k, v in obj.items():
key_verifier(k)
value_verifier(v)
verify_value = verify_map
elif isinstance(dataType, StructType):
verifiers = []
for f in dataType.fields:
verifier = _make_type_verifier(f.dataType, f.nullable, name=new_name(f.name))
verifiers.append((f.name, verifier))
def verify_struct(obj):
assert_acceptable_types(obj)
if isinstance(obj, dict):
for f, verifier in verifiers:
verifier(obj.get(f))
elif isinstance(obj, Row) and getattr(obj, "__from_dict__", False):
# the order in obj could be different than dataType.fields
for f, verifier in verifiers:
verifier(obj[f])
elif isinstance(obj, (tuple, list)):
if len(obj) != len(verifiers):
raise ValueError(
new_msg("Length of object (%d) does not match with "
"length of fields (%d)" % (len(obj), len(verifiers))))
for v, (_, verifier) in zip(obj, verifiers):
verifier(v)
elif hasattr(obj, "__dict__"):
d = obj.__dict__
for f, verifier in verifiers:
verifier(d.get(f))
else:
raise TypeError(new_msg("StructType can not accept object %r in type %s"
% (obj, type(obj))))
verify_value = verify_struct
else:
def verify_default(obj):
assert_acceptable_types(obj)
verify_acceptable_types(obj)
verify_value = verify_default
def verify(obj):
if not verify_nullability(obj):
verify_value(obj)
return verify |
Convert Spark data type to pyarrow type | def to_arrow_type(dt):
""" Convert Spark data type to pyarrow type
"""
import pyarrow as pa
if type(dt) == BooleanType:
arrow_type = pa.bool_()
elif type(dt) == ByteType:
arrow_type = pa.int8()
elif type(dt) == ShortType:
arrow_type = pa.int16()
elif type(dt) == IntegerType:
arrow_type = pa.int32()
elif type(dt) == LongType:
arrow_type = pa.int64()
elif type(dt) == FloatType:
arrow_type = pa.float32()
elif type(dt) == DoubleType:
arrow_type = pa.float64()
elif type(dt) == DecimalType:
arrow_type = pa.decimal128(dt.precision, dt.scale)
elif type(dt) == StringType:
arrow_type = pa.string()
elif type(dt) == BinaryType:
arrow_type = pa.binary()
elif type(dt) == DateType:
arrow_type = pa.date32()
elif type(dt) == TimestampType:
# Timestamps should be in UTC, JVM Arrow timestamps require a timezone to be read
arrow_type = pa.timestamp('us', tz='UTC')
elif type(dt) == ArrayType:
if type(dt.elementType) in [StructType, TimestampType]:
raise TypeError("Unsupported type in conversion to Arrow: " + str(dt))
arrow_type = pa.list_(to_arrow_type(dt.elementType))
elif type(dt) == StructType:
if any(type(field.dataType) == StructType for field in dt):
raise TypeError("Nested StructType not supported in conversion to Arrow")
fields = [pa.field(field.name, to_arrow_type(field.dataType), nullable=field.nullable)
for field in dt]
arrow_type = pa.struct(fields)
else:
raise TypeError("Unsupported type in conversion to Arrow: " + str(dt))
return arrow_type |
Convert a schema from Spark to Arrow | def to_arrow_schema(schema):
""" Convert a schema from Spark to Arrow
"""
import pyarrow as pa
fields = [pa.field(field.name, to_arrow_type(field.dataType), nullable=field.nullable)
for field in schema]
return pa.schema(fields) |
Convert pyarrow type to Spark data type. | def from_arrow_type(at):
""" Convert pyarrow type to Spark data type.
"""
import pyarrow.types as types
if types.is_boolean(at):
spark_type = BooleanType()
elif types.is_int8(at):
spark_type = ByteType()
elif types.is_int16(at):
spark_type = ShortType()
elif types.is_int32(at):
spark_type = IntegerType()
elif types.is_int64(at):
spark_type = LongType()
elif types.is_float32(at):
spark_type = FloatType()
elif types.is_float64(at):
spark_type = DoubleType()
elif types.is_decimal(at):
spark_type = DecimalType(precision=at.precision, scale=at.scale)
elif types.is_string(at):
spark_type = StringType()
elif types.is_binary(at):
spark_type = BinaryType()
elif types.is_date32(at):
spark_type = DateType()
elif types.is_timestamp(at):
spark_type = TimestampType()
elif types.is_list(at):
if types.is_timestamp(at.value_type):
raise TypeError("Unsupported type in conversion from Arrow: " + str(at))
spark_type = ArrayType(from_arrow_type(at.value_type))
elif types.is_struct(at):
if any(types.is_struct(field.type) for field in at):
raise TypeError("Nested StructType not supported in conversion from Arrow: " + str(at))
return StructType(
[StructField(field.name, from_arrow_type(field.type), nullable=field.nullable)
for field in at])
else:
raise TypeError("Unsupported type in conversion from Arrow: " + str(at))
return spark_type |
Convert schema from Arrow to Spark. | def from_arrow_schema(arrow_schema):
""" Convert schema from Arrow to Spark.
"""
return StructType(
[StructField(field.name, from_arrow_type(field.type), nullable=field.nullable)
for field in arrow_schema]) |
Convert timezone aware timestamps to timezone-naive in the specified timezone or local timezone.
If the input series is not a timestamp series, then the same series is returned. If the input
series is a timestamp series, then a converted series is returned.
:param s: pandas.Series
:param timezone: the timezone to convert. if None then use local timezone
:return pandas.Series that have been converted to tz-naive | def _check_series_localize_timestamps(s, timezone):
"""
Convert timezone aware timestamps to timezone-naive in the specified timezone or local timezone.
If the input series is not a timestamp series, then the same series is returned. If the input
series is a timestamp series, then a converted series is returned.
:param s: pandas.Series
:param timezone: the timezone to convert. if None then use local timezone
:return pandas.Series that have been converted to tz-naive
"""
from pyspark.sql.utils import require_minimum_pandas_version
require_minimum_pandas_version()
from pandas.api.types import is_datetime64tz_dtype
tz = timezone or _get_local_timezone()
# TODO: handle nested timestamps, such as ArrayType(TimestampType())?
if is_datetime64tz_dtype(s.dtype):
return s.dt.tz_convert(tz).dt.tz_localize(None)
else:
return s |
Convert timezone aware timestamps to timezone-naive in the specified timezone or local timezone
:param pdf: pandas.DataFrame
:param timezone: the timezone to convert. if None then use local timezone
:return pandas.DataFrame where any timezone aware columns have been converted to tz-naive | def _check_dataframe_localize_timestamps(pdf, timezone):
"""
Convert timezone aware timestamps to timezone-naive in the specified timezone or local timezone
:param pdf: pandas.DataFrame
:param timezone: the timezone to convert. if None then use local timezone
:return pandas.DataFrame where any timezone aware columns have been converted to tz-naive
"""
from pyspark.sql.utils import require_minimum_pandas_version
require_minimum_pandas_version()
for column, series in pdf.iteritems():
pdf[column] = _check_series_localize_timestamps(series, timezone)
return pdf |
Convert a tz-naive timestamp in the specified timezone or local timezone to UTC normalized for
Spark internal storage
:param s: a pandas.Series
:param timezone: the timezone to convert. if None then use local timezone
:return pandas.Series where if it is a timestamp, has been UTC normalized without a time zone | def _check_series_convert_timestamps_internal(s, timezone):
"""
Convert a tz-naive timestamp in the specified timezone or local timezone to UTC normalized for
Spark internal storage
:param s: a pandas.Series
:param timezone: the timezone to convert. if None then use local timezone
:return pandas.Series where if it is a timestamp, has been UTC normalized without a time zone
"""
from pyspark.sql.utils import require_minimum_pandas_version
require_minimum_pandas_version()
from pandas.api.types import is_datetime64_dtype, is_datetime64tz_dtype
# TODO: handle nested timestamps, such as ArrayType(TimestampType())?
if is_datetime64_dtype(s.dtype):
# When tz_localize a tz-naive timestamp, the result is ambiguous if the tz-naive
# timestamp is during the hour when the clock is adjusted backward during due to
# daylight saving time (dst).
# E.g., for America/New_York, the clock is adjusted backward on 2015-11-01 2:00 to
# 2015-11-01 1:00 from dst-time to standard time, and therefore, when tz_localize
# a tz-naive timestamp 2015-11-01 1:30 with America/New_York timezone, it can be either
# dst time (2015-01-01 1:30-0400) or standard time (2015-11-01 1:30-0500).
#
# Here we explicit choose to use standard time. This matches the default behavior of
# pytz.
#
# Here are some code to help understand this behavior:
# >>> import datetime
# >>> import pandas as pd
# >>> import pytz
# >>>
# >>> t = datetime.datetime(2015, 11, 1, 1, 30)
# >>> ts = pd.Series([t])
# >>> tz = pytz.timezone('America/New_York')
# >>>
# >>> ts.dt.tz_localize(tz, ambiguous=True)
# 0 2015-11-01 01:30:00-04:00
# dtype: datetime64[ns, America/New_York]
# >>>
# >>> ts.dt.tz_localize(tz, ambiguous=False)
# 0 2015-11-01 01:30:00-05:00
# dtype: datetime64[ns, America/New_York]
# >>>
# >>> str(tz.localize(t))
# '2015-11-01 01:30:00-05:00'
tz = timezone or _get_local_timezone()
return s.dt.tz_localize(tz, ambiguous=False).dt.tz_convert('UTC')
elif is_datetime64tz_dtype(s.dtype):
return s.dt.tz_convert('UTC')
else:
return s |
Convert timestamp to timezone-naive in the specified timezone or local timezone
:param s: a pandas.Series
:param from_timezone: the timezone to convert from. if None then use local timezone
:param to_timezone: the timezone to convert to. if None then use local timezone
:return pandas.Series where if it is a timestamp, has been converted to tz-naive | def _check_series_convert_timestamps_localize(s, from_timezone, to_timezone):
"""
Convert timestamp to timezone-naive in the specified timezone or local timezone
:param s: a pandas.Series
:param from_timezone: the timezone to convert from. if None then use local timezone
:param to_timezone: the timezone to convert to. if None then use local timezone
:return pandas.Series where if it is a timestamp, has been converted to tz-naive
"""
from pyspark.sql.utils import require_minimum_pandas_version
require_minimum_pandas_version()
import pandas as pd
from pandas.api.types import is_datetime64tz_dtype, is_datetime64_dtype
from_tz = from_timezone or _get_local_timezone()
to_tz = to_timezone or _get_local_timezone()
# TODO: handle nested timestamps, such as ArrayType(TimestampType())?
if is_datetime64tz_dtype(s.dtype):
return s.dt.tz_convert(to_tz).dt.tz_localize(None)
elif is_datetime64_dtype(s.dtype) and from_tz != to_tz:
# `s.dt.tz_localize('tzlocal()')` doesn't work properly when including NaT.
return s.apply(
lambda ts: ts.tz_localize(from_tz, ambiguous=False).tz_convert(to_tz).tz_localize(None)
if ts is not pd.NaT else pd.NaT)
else:
return s |
Construct a StructType by adding new elements to it to define the schema. The method accepts
either:
a) A single parameter which is a StructField object.
b) Between 2 and 4 parameters as (name, data_type, nullable (optional),
metadata(optional). The data_type parameter may be either a String or a
DataType object.
>>> struct1 = StructType().add("f1", StringType(), True).add("f2", StringType(), True, None)
>>> struct2 = StructType([StructField("f1", StringType(), True), \\
... StructField("f2", StringType(), True, None)])
>>> struct1 == struct2
True
>>> struct1 = StructType().add(StructField("f1", StringType(), True))
>>> struct2 = StructType([StructField("f1", StringType(), True)])
>>> struct1 == struct2
True
>>> struct1 = StructType().add("f1", "string", True)
>>> struct2 = StructType([StructField("f1", StringType(), True)])
>>> struct1 == struct2
True
:param field: Either the name of the field or a StructField object
:param data_type: If present, the DataType of the StructField to create
:param nullable: Whether the field to add should be nullable (default True)
:param metadata: Any additional metadata (default None)
:return: a new updated StructType | def add(self, field, data_type=None, nullable=True, metadata=None):
"""
Construct a StructType by adding new elements to it to define the schema. The method accepts
either:
a) A single parameter which is a StructField object.
b) Between 2 and 4 parameters as (name, data_type, nullable (optional),
metadata(optional). The data_type parameter may be either a String or a
DataType object.
>>> struct1 = StructType().add("f1", StringType(), True).add("f2", StringType(), True, None)
>>> struct2 = StructType([StructField("f1", StringType(), True), \\
... StructField("f2", StringType(), True, None)])
>>> struct1 == struct2
True
>>> struct1 = StructType().add(StructField("f1", StringType(), True))
>>> struct2 = StructType([StructField("f1", StringType(), True)])
>>> struct1 == struct2
True
>>> struct1 = StructType().add("f1", "string", True)
>>> struct2 = StructType([StructField("f1", StringType(), True)])
>>> struct1 == struct2
True
:param field: Either the name of the field or a StructField object
:param data_type: If present, the DataType of the StructField to create
:param nullable: Whether the field to add should be nullable (default True)
:param metadata: Any additional metadata (default None)
:return: a new updated StructType
"""
if isinstance(field, StructField):
self.fields.append(field)
self.names.append(field.name)
else:
if isinstance(field, str) and data_type is None:
raise ValueError("Must specify DataType if passing name of struct_field to create.")
if isinstance(data_type, str):
data_type_f = _parse_datatype_json_value(data_type)
else:
data_type_f = data_type
self.fields.append(StructField(field, data_type_f, nullable, metadata))
self.names.append(field)
# Precalculated list of fields that need conversion with fromInternal/toInternal functions
self._needConversion = [f.needConversion() for f in self]
self._needSerializeAnyField = any(self._needConversion)
return self |
Cache the sqlType() into class, because it's heavy used in `toInternal`. | def _cachedSqlType(cls):
"""
Cache the sqlType() into class, because it's heavy used in `toInternal`.
"""
if not hasattr(cls, "_cached_sql_type"):
cls._cached_sql_type = cls.sqlType()
return cls._cached_sql_type |
Return as an dict
:param recursive: turns the nested Row as dict (default: False).
>>> Row(name="Alice", age=11).asDict() == {'name': 'Alice', 'age': 11}
True
>>> row = Row(key=1, value=Row(name='a', age=2))
>>> row.asDict() == {'key': 1, 'value': Row(age=2, name='a')}
True
>>> row.asDict(True) == {'key': 1, 'value': {'name': 'a', 'age': 2}}
True | def asDict(self, recursive=False):
"""
Return as an dict
:param recursive: turns the nested Row as dict (default: False).
>>> Row(name="Alice", age=11).asDict() == {'name': 'Alice', 'age': 11}
True
>>> row = Row(key=1, value=Row(name='a', age=2))
>>> row.asDict() == {'key': 1, 'value': Row(age=2, name='a')}
True
>>> row.asDict(True) == {'key': 1, 'value': {'name': 'a', 'age': 2}}
True
"""
if not hasattr(self, "__fields__"):
raise TypeError("Cannot convert a Row class into dict")
if recursive:
def conv(obj):
if isinstance(obj, Row):
return obj.asDict(True)
elif isinstance(obj, list):
return [conv(o) for o in obj]
elif isinstance(obj, dict):
return dict((k, conv(v)) for k, v in obj.items())
else:
return obj
return dict(zip(self.__fields__, (conv(o) for o in self)))
else:
return dict(zip(self.__fields__, self)) |
Gets summary (e.g. residuals, mse, r-squared ) of model on
training set. An exception is thrown if
`trainingSummary is None`. | def summary(self):
"""
Gets summary (e.g. residuals, mse, r-squared ) of model on
training set. An exception is thrown if
`trainingSummary is None`.
"""
if self.hasSummary:
return LinearRegressionTrainingSummary(super(LinearRegressionModel, self).summary)
else:
raise RuntimeError("No training summary available for this %s" %
self.__class__.__name__) |
Evaluates the model on a test dataset.
:param dataset:
Test dataset to evaluate model on, where dataset is an
instance of :py:class:`pyspark.sql.DataFrame` | def evaluate(self, dataset):
"""
Evaluates the model on a test dataset.
:param dataset:
Test dataset to evaluate model on, where dataset is an
instance of :py:class:`pyspark.sql.DataFrame`
"""
if not isinstance(dataset, DataFrame):
raise ValueError("dataset must be a DataFrame but got %s." % type(dataset))
java_lr_summary = self._call_java("evaluate", dataset)
return LinearRegressionSummary(java_lr_summary) |
Gets summary (e.g. residuals, deviance, pValues) of model on
training set. An exception is thrown if
`trainingSummary is None`. | def summary(self):
"""
Gets summary (e.g. residuals, deviance, pValues) of model on
training set. An exception is thrown if
`trainingSummary is None`.
"""
if self.hasSummary:
return GeneralizedLinearRegressionTrainingSummary(
super(GeneralizedLinearRegressionModel, self).summary)
else:
raise RuntimeError("No training summary available for this %s" %
self.__class__.__name__) |
Evaluates the model on a test dataset.
:param dataset:
Test dataset to evaluate model on, where dataset is an
instance of :py:class:`pyspark.sql.DataFrame` | def evaluate(self, dataset):
"""
Evaluates the model on a test dataset.
:param dataset:
Test dataset to evaluate model on, where dataset is an
instance of :py:class:`pyspark.sql.DataFrame`
"""
if not isinstance(dataset, DataFrame):
raise ValueError("dataset must be a DataFrame but got %s." % type(dataset))
java_glr_summary = self._call_java("evaluate", dataset)
return GeneralizedLinearRegressionSummary(java_glr_summary) |
Get all the directories | def _get_local_dirs(sub):
""" Get all the directories """
path = os.environ.get("SPARK_LOCAL_DIRS", "/tmp")
dirs = path.split(",")
if len(dirs) > 1:
# different order in different processes and instances
rnd = random.Random(os.getpid() + id(dirs))
random.shuffle(dirs, rnd.random)
return [os.path.join(d, "python", str(os.getpid()), sub) for d in dirs] |
Choose one directory for spill by number n | def _get_spill_dir(self, n):
""" Choose one directory for spill by number n """
return os.path.join(self.localdirs[n % len(self.localdirs)], str(n)) |
Combine the items by creator and combiner | def mergeValues(self, iterator):
""" Combine the items by creator and combiner """
# speedup attribute lookup
creator, comb = self.agg.createCombiner, self.agg.mergeValue
c, data, pdata, hfun, batch = 0, self.data, self.pdata, self._partition, self.batch
limit = self.memory_limit
for k, v in iterator:
d = pdata[hfun(k)] if pdata else data
d[k] = comb(d[k], v) if k in d else creator(v)
c += 1
if c >= batch:
if get_used_memory() >= limit:
self._spill()
limit = self._next_limit()
batch /= 2
c = 0
else:
batch *= 1.5
if get_used_memory() >= limit:
self._spill() |
Merge (K,V) pair by mergeCombiner | def mergeCombiners(self, iterator, limit=None):
""" Merge (K,V) pair by mergeCombiner """
if limit is None:
limit = self.memory_limit
# speedup attribute lookup
comb, hfun, objsize = self.agg.mergeCombiners, self._partition, self._object_size
c, data, pdata, batch = 0, self.data, self.pdata, self.batch
for k, v in iterator:
d = pdata[hfun(k)] if pdata else data
d[k] = comb(d[k], v) if k in d else v
if not limit:
continue
c += objsize(v)
if c > batch:
if get_used_memory() > limit:
self._spill()
limit = self._next_limit()
batch /= 2
c = 0
else:
batch *= 1.5
if limit and get_used_memory() >= limit:
self._spill() |
dump already partitioned data into disks.
It will dump the data in batch for better performance. | def _spill(self):
"""
dump already partitioned data into disks.
It will dump the data in batch for better performance.
"""
global MemoryBytesSpilled, DiskBytesSpilled
path = self._get_spill_dir(self.spills)
if not os.path.exists(path):
os.makedirs(path)
used_memory = get_used_memory()
if not self.pdata:
# The data has not been partitioned, it will iterator the
# dataset once, write them into different files, has no
# additional memory. It only called when the memory goes
# above limit at the first time.
# open all the files for writing
streams = [open(os.path.join(path, str(i)), 'wb')
for i in range(self.partitions)]
for k, v in self.data.items():
h = self._partition(k)
# put one item in batch, make it compatible with load_stream
# it will increase the memory if dump them in batch
self.serializer.dump_stream([(k, v)], streams[h])
for s in streams:
DiskBytesSpilled += s.tell()
s.close()
self.data.clear()
self.pdata.extend([{} for i in range(self.partitions)])
else:
for i in range(self.partitions):
p = os.path.join(path, str(i))
with open(p, "wb") as f:
# dump items in batch
self.serializer.dump_stream(iter(self.pdata[i].items()), f)
self.pdata[i].clear()
DiskBytesSpilled += os.path.getsize(p)
self.spills += 1
gc.collect() # release the memory as much as possible
MemoryBytesSpilled += max(used_memory - get_used_memory(), 0) << 20 |
Return all merged items as iterator | def items(self):
""" Return all merged items as iterator """
if not self.pdata and not self.spills:
return iter(self.data.items())
return self._external_items() |
Return all partitioned items as iterator | def _external_items(self):
""" Return all partitioned items as iterator """
assert not self.data
if any(self.pdata):
self._spill()
# disable partitioning and spilling when merge combiners from disk
self.pdata = []
try:
for i in range(self.partitions):
for v in self._merged_items(i):
yield v
self.data.clear()
# remove the merged partition
for j in range(self.spills):
path = self._get_spill_dir(j)
os.remove(os.path.join(path, str(i)))
finally:
self._cleanup() |
merge the partitioned items and return the as iterator
If one partition can not be fit in memory, then them will be
partitioned and merged recursively. | def _recursive_merged_items(self, index):
"""
merge the partitioned items and return the as iterator
If one partition can not be fit in memory, then them will be
partitioned and merged recursively.
"""
subdirs = [os.path.join(d, "parts", str(index)) for d in self.localdirs]
m = ExternalMerger(self.agg, self.memory_limit, self.serializer, subdirs,
self.scale * self.partitions, self.partitions, self.batch)
m.pdata = [{} for _ in range(self.partitions)]
limit = self._next_limit()
for j in range(self.spills):
path = self._get_spill_dir(j)
p = os.path.join(path, str(index))
with open(p, 'rb') as f:
m.mergeCombiners(self.serializer.load_stream(f), 0)
if get_used_memory() > limit:
m._spill()
limit = self._next_limit()
return m._external_items() |
Choose one directory for spill by number n | def _get_path(self, n):
""" Choose one directory for spill by number n """
d = self.local_dirs[n % len(self.local_dirs)]
if not os.path.exists(d):
os.makedirs(d)
return os.path.join(d, str(n)) |
Sort the elements in iterator, do external sort when the memory
goes above the limit. | def sorted(self, iterator, key=None, reverse=False):
"""
Sort the elements in iterator, do external sort when the memory
goes above the limit.
"""
global MemoryBytesSpilled, DiskBytesSpilled
batch, limit = 100, self._next_limit()
chunks, current_chunk = [], []
iterator = iter(iterator)
while True:
# pick elements in batch
chunk = list(itertools.islice(iterator, batch))
current_chunk.extend(chunk)
if len(chunk) < batch:
break
used_memory = get_used_memory()
if used_memory > limit:
# sort them inplace will save memory
current_chunk.sort(key=key, reverse=reverse)
path = self._get_path(len(chunks))
with open(path, 'wb') as f:
self.serializer.dump_stream(current_chunk, f)
def load(f):
for v in self.serializer.load_stream(f):
yield v
# close the file explicit once we consume all the items
# to avoid ResourceWarning in Python3
f.close()
chunks.append(load(open(path, 'rb')))
current_chunk = []
MemoryBytesSpilled += max(used_memory - get_used_memory(), 0) << 20
DiskBytesSpilled += os.path.getsize(path)
os.unlink(path) # data will be deleted after close
elif not chunks:
batch = min(int(batch * 1.5), 10000)
current_chunk.sort(key=key, reverse=reverse)
if not chunks:
return current_chunk
if current_chunk:
chunks.append(iter(current_chunk))
return heapq.merge(chunks, key=key, reverse=reverse) |
dump the values into disk | def _spill(self):
""" dump the values into disk """
global MemoryBytesSpilled, DiskBytesSpilled
if self._file is None:
self._open_file()
used_memory = get_used_memory()
pos = self._file.tell()
self._ser.dump_stream(self.values, self._file)
self.values = []
gc.collect()
DiskBytesSpilled += self._file.tell() - pos
MemoryBytesSpilled += max(used_memory - get_used_memory(), 0) << 20 |
dump already partitioned data into disks. | def _spill(self):
"""
dump already partitioned data into disks.
"""
global MemoryBytesSpilled, DiskBytesSpilled
path = self._get_spill_dir(self.spills)
if not os.path.exists(path):
os.makedirs(path)
used_memory = get_used_memory()
if not self.pdata:
# The data has not been partitioned, it will iterator the
# data once, write them into different files, has no
# additional memory. It only called when the memory goes
# above limit at the first time.
# open all the files for writing
streams = [open(os.path.join(path, str(i)), 'wb')
for i in range(self.partitions)]
# If the number of keys is small, then the overhead of sort is small
# sort them before dumping into disks
self._sorted = len(self.data) < self.SORT_KEY_LIMIT
if self._sorted:
self.serializer = self.flattened_serializer()
for k in sorted(self.data.keys()):
h = self._partition(k)
self.serializer.dump_stream([(k, self.data[k])], streams[h])
else:
for k, v in self.data.items():
h = self._partition(k)
self.serializer.dump_stream([(k, v)], streams[h])
for s in streams:
DiskBytesSpilled += s.tell()
s.close()
self.data.clear()
# self.pdata is cached in `mergeValues` and `mergeCombiners`
self.pdata.extend([{} for i in range(self.partitions)])
else:
for i in range(self.partitions):
p = os.path.join(path, str(i))
with open(p, "wb") as f:
# dump items in batch
if self._sorted:
# sort by key only (stable)
sorted_items = sorted(self.pdata[i].items(), key=operator.itemgetter(0))
self.serializer.dump_stream(sorted_items, f)
else:
self.serializer.dump_stream(self.pdata[i].items(), f)
self.pdata[i].clear()
DiskBytesSpilled += os.path.getsize(p)
self.spills += 1
gc.collect() # release the memory as much as possible
MemoryBytesSpilled += max(used_memory - get_used_memory(), 0) << 20 |
load a partition from disk, then sort and group by key | def _merge_sorted_items(self, index):
""" load a partition from disk, then sort and group by key """
def load_partition(j):
path = self._get_spill_dir(j)
p = os.path.join(path, str(index))
with open(p, 'rb', 65536) as f:
for v in self.serializer.load_stream(f):
yield v
disk_items = [load_partition(j) for j in range(self.spills)]
if self._sorted:
# all the partitions are already sorted
sorted_items = heapq.merge(disk_items, key=operator.itemgetter(0))
else:
# Flatten the combined values, so it will not consume huge
# memory during merging sort.
ser = self.flattened_serializer()
sorter = ExternalSorter(self.memory_limit, ser)
sorted_items = sorter.sorted(itertools.chain(*disk_items),
key=operator.itemgetter(0))
return ((k, vs) for k, vs in GroupByKey(sorted_items)) |
Called by a worker process after the fork(). | def worker(sock, authenticated):
"""
Called by a worker process after the fork().
"""
signal.signal(SIGHUP, SIG_DFL)
signal.signal(SIGCHLD, SIG_DFL)
signal.signal(SIGTERM, SIG_DFL)
# restore the handler for SIGINT,
# it's useful for debugging (show the stacktrace before exit)
signal.signal(SIGINT, signal.default_int_handler)
# Read the socket using fdopen instead of socket.makefile() because the latter
# seems to be very slow; note that we need to dup() the file descriptor because
# otherwise writes also cause a seek that makes us miss data on the read side.
infile = os.fdopen(os.dup(sock.fileno()), "rb", 65536)
outfile = os.fdopen(os.dup(sock.fileno()), "wb", 65536)
if not authenticated:
client_secret = UTF8Deserializer().loads(infile)
if os.environ["PYTHON_WORKER_FACTORY_SECRET"] == client_secret:
write_with_length("ok".encode("utf-8"), outfile)
outfile.flush()
else:
write_with_length("err".encode("utf-8"), outfile)
outfile.flush()
sock.close()
return 1
exit_code = 0
try:
worker_main(infile, outfile)
except SystemExit as exc:
exit_code = compute_real_exit_code(exc.code)
finally:
try:
outfile.flush()
except Exception:
pass
return exit_code |
This function returns consistent hash code for builtin types, especially
for None and tuple with None.
The algorithm is similar to that one used by CPython 2.7
>>> portable_hash(None)
0
>>> portable_hash((None, 1)) & 0xffffffff
219750521 | def portable_hash(x):
"""
This function returns consistent hash code for builtin types, especially
for None and tuple with None.
The algorithm is similar to that one used by CPython 2.7
>>> portable_hash(None)
0
>>> portable_hash((None, 1)) & 0xffffffff
219750521
"""
if sys.version_info >= (3, 2, 3) and 'PYTHONHASHSEED' not in os.environ:
raise Exception("Randomness of hash of string should be disabled via PYTHONHASHSEED")
if x is None:
return 0
if isinstance(x, tuple):
h = 0x345678
for i in x:
h ^= portable_hash(i)
h *= 1000003
h &= sys.maxsize
h ^= len(x)
if h == -1:
h = -2
return int(h)
return hash(x) |
Parse a memory string in the format supported by Java (e.g. 1g, 200m) and
return the value in MiB
>>> _parse_memory("256m")
256
>>> _parse_memory("2g")
2048 | def _parse_memory(s):
"""
Parse a memory string in the format supported by Java (e.g. 1g, 200m) and
return the value in MiB
>>> _parse_memory("256m")
256
>>> _parse_memory("2g")
2048
"""
units = {'g': 1024, 'm': 1, 't': 1 << 20, 'k': 1.0 / 1024}
if s[-1].lower() not in units:
raise ValueError("invalid format: " + s)
return int(float(s[:-1]) * units[s[-1].lower()]) |
Ignore the 'u' prefix of string in doc tests, to make it works
in both python 2 and 3 | def ignore_unicode_prefix(f):
"""
Ignore the 'u' prefix of string in doc tests, to make it works
in both python 2 and 3
"""
if sys.version >= '3':
# the representation of unicode string in Python 3 does not have prefix 'u',
# so remove the prefix 'u' for doc tests
literal_re = re.compile(r"(\W|^)[uU](['])", re.UNICODE)
f.__doc__ = literal_re.sub(r'\1\2', f.__doc__)
return f |
Persist this RDD with the default storage level (C{MEMORY_ONLY}). | def cache(self):
"""
Persist this RDD with the default storage level (C{MEMORY_ONLY}).
"""
self.is_cached = True
self.persist(StorageLevel.MEMORY_ONLY)
return self |
Set this RDD's storage level to persist its values across operations
after the first time it is computed. This can only be used to assign
a new storage level if the RDD does not have a storage level set yet.
If no storage level is specified defaults to (C{MEMORY_ONLY}).
>>> rdd = sc.parallelize(["b", "a", "c"])
>>> rdd.persist().is_cached
True | def persist(self, storageLevel=StorageLevel.MEMORY_ONLY):
"""
Set this RDD's storage level to persist its values across operations
after the first time it is computed. This can only be used to assign
a new storage level if the RDD does not have a storage level set yet.
If no storage level is specified defaults to (C{MEMORY_ONLY}).
>>> rdd = sc.parallelize(["b", "a", "c"])
>>> rdd.persist().is_cached
True
"""
self.is_cached = True
javaStorageLevel = self.ctx._getJavaStorageLevel(storageLevel)
self._jrdd.persist(javaStorageLevel)
return self |
Mark the RDD as non-persistent, and remove all blocks for it from
memory and disk.
.. versionchanged:: 3.0.0
Added optional argument `blocking` to specify whether to block until all
blocks are deleted. | def unpersist(self, blocking=False):
"""
Mark the RDD as non-persistent, and remove all blocks for it from
memory and disk.
.. versionchanged:: 3.0.0
Added optional argument `blocking` to specify whether to block until all
blocks are deleted.
"""
self.is_cached = False
self._jrdd.unpersist(blocking)
return self |
Gets the name of the file to which this RDD was checkpointed
Not defined if RDD is checkpointed locally. | def getCheckpointFile(self):
"""
Gets the name of the file to which this RDD was checkpointed
Not defined if RDD is checkpointed locally.
"""
checkpointFile = self._jrdd.rdd().getCheckpointFile()
if checkpointFile.isDefined():
return checkpointFile.get() |
Return a new RDD by applying a function to each element of this RDD.
>>> rdd = sc.parallelize(["b", "a", "c"])
>>> sorted(rdd.map(lambda x: (x, 1)).collect())
[('a', 1), ('b', 1), ('c', 1)] | def map(self, f, preservesPartitioning=False):
"""
Return a new RDD by applying a function to each element of this RDD.
>>> rdd = sc.parallelize(["b", "a", "c"])
>>> sorted(rdd.map(lambda x: (x, 1)).collect())
[('a', 1), ('b', 1), ('c', 1)]
"""
def func(_, iterator):
return map(fail_on_stopiteration(f), iterator)
return self.mapPartitionsWithIndex(func, preservesPartitioning) |
Return a new RDD by first applying a function to all elements of this
RDD, and then flattening the results.
>>> rdd = sc.parallelize([2, 3, 4])
>>> sorted(rdd.flatMap(lambda x: range(1, x)).collect())
[1, 1, 1, 2, 2, 3]
>>> sorted(rdd.flatMap(lambda x: [(x, x), (x, x)]).collect())
[(2, 2), (2, 2), (3, 3), (3, 3), (4, 4), (4, 4)] | def flatMap(self, f, preservesPartitioning=False):
"""
Return a new RDD by first applying a function to all elements of this
RDD, and then flattening the results.
>>> rdd = sc.parallelize([2, 3, 4])
>>> sorted(rdd.flatMap(lambda x: range(1, x)).collect())
[1, 1, 1, 2, 2, 3]
>>> sorted(rdd.flatMap(lambda x: [(x, x), (x, x)]).collect())
[(2, 2), (2, 2), (3, 3), (3, 3), (4, 4), (4, 4)]
"""
def func(s, iterator):
return chain.from_iterable(map(fail_on_stopiteration(f), iterator))
return self.mapPartitionsWithIndex(func, preservesPartitioning) |
Return a new RDD by applying a function to each partition of this RDD.
>>> rdd = sc.parallelize([1, 2, 3, 4], 2)
>>> def f(iterator): yield sum(iterator)
>>> rdd.mapPartitions(f).collect()
[3, 7] | def mapPartitions(self, f, preservesPartitioning=False):
"""
Return a new RDD by applying a function to each partition of this RDD.
>>> rdd = sc.parallelize([1, 2, 3, 4], 2)
>>> def f(iterator): yield sum(iterator)
>>> rdd.mapPartitions(f).collect()
[3, 7]
"""
def func(s, iterator):
return f(iterator)
return self.mapPartitionsWithIndex(func, preservesPartitioning) |
Deprecated: use mapPartitionsWithIndex instead.
Return a new RDD by applying a function to each partition of this RDD,
while tracking the index of the original partition.
>>> rdd = sc.parallelize([1, 2, 3, 4], 4)
>>> def f(splitIndex, iterator): yield splitIndex
>>> rdd.mapPartitionsWithSplit(f).sum()
6 | def mapPartitionsWithSplit(self, f, preservesPartitioning=False):
"""
Deprecated: use mapPartitionsWithIndex instead.
Return a new RDD by applying a function to each partition of this RDD,
while tracking the index of the original partition.
>>> rdd = sc.parallelize([1, 2, 3, 4], 4)
>>> def f(splitIndex, iterator): yield splitIndex
>>> rdd.mapPartitionsWithSplit(f).sum()
6
"""
warnings.warn("mapPartitionsWithSplit is deprecated; "
"use mapPartitionsWithIndex instead", DeprecationWarning, stacklevel=2)
return self.mapPartitionsWithIndex(f, preservesPartitioning) |
Return a new RDD containing the distinct elements in this RDD.
>>> sorted(sc.parallelize([1, 1, 2, 3]).distinct().collect())
[1, 2, 3] | def distinct(self, numPartitions=None):
"""
Return a new RDD containing the distinct elements in this RDD.
>>> sorted(sc.parallelize([1, 1, 2, 3]).distinct().collect())
[1, 2, 3]
"""
return self.map(lambda x: (x, None)) \
.reduceByKey(lambda x, _: x, numPartitions) \
.map(lambda x: x[0]) |
Return a sampled subset of this RDD.
:param withReplacement: can elements be sampled multiple times (replaced when sampled out)
:param fraction: expected size of the sample as a fraction of this RDD's size
without replacement: probability that each element is chosen; fraction must be [0, 1]
with replacement: expected number of times each element is chosen; fraction must be >= 0
:param seed: seed for the random number generator
.. note:: This is not guaranteed to provide exactly the fraction specified of the total
count of the given :class:`DataFrame`.
>>> rdd = sc.parallelize(range(100), 4)
>>> 6 <= rdd.sample(False, 0.1, 81).count() <= 14
True | def sample(self, withReplacement, fraction, seed=None):
"""
Return a sampled subset of this RDD.
:param withReplacement: can elements be sampled multiple times (replaced when sampled out)
:param fraction: expected size of the sample as a fraction of this RDD's size
without replacement: probability that each element is chosen; fraction must be [0, 1]
with replacement: expected number of times each element is chosen; fraction must be >= 0
:param seed: seed for the random number generator
.. note:: This is not guaranteed to provide exactly the fraction specified of the total
count of the given :class:`DataFrame`.
>>> rdd = sc.parallelize(range(100), 4)
>>> 6 <= rdd.sample(False, 0.1, 81).count() <= 14
True
"""
assert fraction >= 0.0, "Negative fraction value: %s" % fraction
return self.mapPartitionsWithIndex(RDDSampler(withReplacement, fraction, seed).func, True) |
Randomly splits this RDD with the provided weights.
:param weights: weights for splits, will be normalized if they don't sum to 1
:param seed: random seed
:return: split RDDs in a list
>>> rdd = sc.parallelize(range(500), 1)
>>> rdd1, rdd2 = rdd.randomSplit([2, 3], 17)
>>> len(rdd1.collect() + rdd2.collect())
500
>>> 150 < rdd1.count() < 250
True
>>> 250 < rdd2.count() < 350
True | def randomSplit(self, weights, seed=None):
"""
Randomly splits this RDD with the provided weights.
:param weights: weights for splits, will be normalized if they don't sum to 1
:param seed: random seed
:return: split RDDs in a list
>>> rdd = sc.parallelize(range(500), 1)
>>> rdd1, rdd2 = rdd.randomSplit([2, 3], 17)
>>> len(rdd1.collect() + rdd2.collect())
500
>>> 150 < rdd1.count() < 250
True
>>> 250 < rdd2.count() < 350
True
"""
s = float(sum(weights))
cweights = [0.0]
for w in weights:
cweights.append(cweights[-1] + w / s)
if seed is None:
seed = random.randint(0, 2 ** 32 - 1)
return [self.mapPartitionsWithIndex(RDDRangeSampler(lb, ub, seed).func, True)
for lb, ub in zip(cweights, cweights[1:])] |
Return a fixed-size sampled subset of this RDD.
.. note:: This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
>>> rdd = sc.parallelize(range(0, 10))
>>> len(rdd.takeSample(True, 20, 1))
20
>>> len(rdd.takeSample(False, 5, 2))
5
>>> len(rdd.takeSample(False, 15, 3))
10 | def takeSample(self, withReplacement, num, seed=None):
"""
Return a fixed-size sampled subset of this RDD.
.. note:: This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
>>> rdd = sc.parallelize(range(0, 10))
>>> len(rdd.takeSample(True, 20, 1))
20
>>> len(rdd.takeSample(False, 5, 2))
5
>>> len(rdd.takeSample(False, 15, 3))
10
"""
numStDev = 10.0
if num < 0:
raise ValueError("Sample size cannot be negative.")
elif num == 0:
return []
initialCount = self.count()
if initialCount == 0:
return []
rand = random.Random(seed)
if (not withReplacement) and num >= initialCount:
# shuffle current RDD and return
samples = self.collect()
rand.shuffle(samples)
return samples
maxSampleSize = sys.maxsize - int(numStDev * sqrt(sys.maxsize))
if num > maxSampleSize:
raise ValueError(
"Sample size cannot be greater than %d." % maxSampleSize)
fraction = RDD._computeFractionForSampleSize(
num, initialCount, withReplacement)
samples = self.sample(withReplacement, fraction, seed).collect()
# If the first sample didn't turn out large enough, keep trying to take samples;
# this shouldn't happen often because we use a big multiplier for their initial size.
# See: scala/spark/RDD.scala
while len(samples) < num:
# TODO: add log warning for when more than one iteration was run
seed = rand.randint(0, sys.maxsize)
samples = self.sample(withReplacement, fraction, seed).collect()
rand.shuffle(samples)
return samples[0:num] |
Returns a sampling rate that guarantees a sample of
size >= sampleSizeLowerBound 99.99% of the time.
How the sampling rate is determined:
Let p = num / total, where num is the sample size and total is the
total number of data points in the RDD. We're trying to compute
q > p such that
- when sampling with replacement, we're drawing each data point
with prob_i ~ Pois(q), where we want to guarantee
Pr[s < num] < 0.0001 for s = sum(prob_i for i from 0 to
total), i.e. the failure rate of not having a sufficiently large
sample < 0.0001. Setting q = p + 5 * sqrt(p/total) is sufficient
to guarantee 0.9999 success rate for num > 12, but we need a
slightly larger q (9 empirically determined).
- when sampling without replacement, we're drawing each data point
with prob_i ~ Binomial(total, fraction) and our choice of q
guarantees 1-delta, or 0.9999 success rate, where success rate is
defined the same as in sampling with replacement. | def _computeFractionForSampleSize(sampleSizeLowerBound, total, withReplacement):
"""
Returns a sampling rate that guarantees a sample of
size >= sampleSizeLowerBound 99.99% of the time.
How the sampling rate is determined:
Let p = num / total, where num is the sample size and total is the
total number of data points in the RDD. We're trying to compute
q > p such that
- when sampling with replacement, we're drawing each data point
with prob_i ~ Pois(q), where we want to guarantee
Pr[s < num] < 0.0001 for s = sum(prob_i for i from 0 to
total), i.e. the failure rate of not having a sufficiently large
sample < 0.0001. Setting q = p + 5 * sqrt(p/total) is sufficient
to guarantee 0.9999 success rate for num > 12, but we need a
slightly larger q (9 empirically determined).
- when sampling without replacement, we're drawing each data point
with prob_i ~ Binomial(total, fraction) and our choice of q
guarantees 1-delta, or 0.9999 success rate, where success rate is
defined the same as in sampling with replacement.
"""
fraction = float(sampleSizeLowerBound) / total
if withReplacement:
numStDev = 5
if (sampleSizeLowerBound < 12):
numStDev = 9
return fraction + numStDev * sqrt(fraction / total)
else:
delta = 0.00005
gamma = - log(delta) / total
return min(1, fraction + gamma + sqrt(gamma * gamma + 2 * gamma * fraction)) |
Return the union of this RDD and another one.
>>> rdd = sc.parallelize([1, 1, 2, 3])
>>> rdd.union(rdd).collect()
[1, 1, 2, 3, 1, 1, 2, 3] | def union(self, other):
"""
Return the union of this RDD and another one.
>>> rdd = sc.parallelize([1, 1, 2, 3])
>>> rdd.union(rdd).collect()
[1, 1, 2, 3, 1, 1, 2, 3]
"""
if self._jrdd_deserializer == other._jrdd_deserializer:
rdd = RDD(self._jrdd.union(other._jrdd), self.ctx,
self._jrdd_deserializer)
else:
# These RDDs contain data in different serialized formats, so we
# must normalize them to the default serializer.
self_copy = self._reserialize()
other_copy = other._reserialize()
rdd = RDD(self_copy._jrdd.union(other_copy._jrdd), self.ctx,
self.ctx.serializer)
if (self.partitioner == other.partitioner and
self.getNumPartitions() == rdd.getNumPartitions()):
rdd.partitioner = self.partitioner
return rdd |
Return the intersection of this RDD and another one. The output will
not contain any duplicate elements, even if the input RDDs did.
.. note:: This method performs a shuffle internally.
>>> rdd1 = sc.parallelize([1, 10, 2, 3, 4, 5])
>>> rdd2 = sc.parallelize([1, 6, 2, 3, 7, 8])
>>> rdd1.intersection(rdd2).collect()
[1, 2, 3] | def intersection(self, other):
"""
Return the intersection of this RDD and another one. The output will
not contain any duplicate elements, even if the input RDDs did.
.. note:: This method performs a shuffle internally.
>>> rdd1 = sc.parallelize([1, 10, 2, 3, 4, 5])
>>> rdd2 = sc.parallelize([1, 6, 2, 3, 7, 8])
>>> rdd1.intersection(rdd2).collect()
[1, 2, 3]
"""
return self.map(lambda v: (v, None)) \
.cogroup(other.map(lambda v: (v, None))) \
.filter(lambda k_vs: all(k_vs[1])) \
.keys() |
Repartition the RDD according to the given partitioner and, within each resulting partition,
sort records by their keys.
>>> rdd = sc.parallelize([(0, 5), (3, 8), (2, 6), (0, 8), (3, 8), (1, 3)])
>>> rdd2 = rdd.repartitionAndSortWithinPartitions(2, lambda x: x % 2, True)
>>> rdd2.glom().collect()
[[(0, 5), (0, 8), (2, 6)], [(1, 3), (3, 8), (3, 8)]] | def repartitionAndSortWithinPartitions(self, numPartitions=None, partitionFunc=portable_hash,
ascending=True, keyfunc=lambda x: x):
"""
Repartition the RDD according to the given partitioner and, within each resulting partition,
sort records by their keys.
>>> rdd = sc.parallelize([(0, 5), (3, 8), (2, 6), (0, 8), (3, 8), (1, 3)])
>>> rdd2 = rdd.repartitionAndSortWithinPartitions(2, lambda x: x % 2, True)
>>> rdd2.glom().collect()
[[(0, 5), (0, 8), (2, 6)], [(1, 3), (3, 8), (3, 8)]]
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
memory = _parse_memory(self.ctx._conf.get("spark.python.worker.memory", "512m"))
serializer = self._jrdd_deserializer
def sortPartition(iterator):
sort = ExternalSorter(memory * 0.9, serializer).sorted
return iter(sort(iterator, key=lambda k_v: keyfunc(k_v[0]), reverse=(not ascending)))
return self.partitionBy(numPartitions, partitionFunc).mapPartitions(sortPartition, True) |
Sorts this RDD, which is assumed to consist of (key, value) pairs.
>>> tmp = [('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
>>> sc.parallelize(tmp).sortByKey().first()
('1', 3)
>>> sc.parallelize(tmp).sortByKey(True, 1).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> sc.parallelize(tmp).sortByKey(True, 2).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> tmp2 = [('Mary', 1), ('had', 2), ('a', 3), ('little', 4), ('lamb', 5)]
>>> tmp2.extend([('whose', 6), ('fleece', 7), ('was', 8), ('white', 9)])
>>> sc.parallelize(tmp2).sortByKey(True, 3, keyfunc=lambda k: k.lower()).collect()
[('a', 3), ('fleece', 7), ('had', 2), ('lamb', 5),...('white', 9), ('whose', 6)] | def sortByKey(self, ascending=True, numPartitions=None, keyfunc=lambda x: x):
"""
Sorts this RDD, which is assumed to consist of (key, value) pairs.
>>> tmp = [('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
>>> sc.parallelize(tmp).sortByKey().first()
('1', 3)
>>> sc.parallelize(tmp).sortByKey(True, 1).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> sc.parallelize(tmp).sortByKey(True, 2).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> tmp2 = [('Mary', 1), ('had', 2), ('a', 3), ('little', 4), ('lamb', 5)]
>>> tmp2.extend([('whose', 6), ('fleece', 7), ('was', 8), ('white', 9)])
>>> sc.parallelize(tmp2).sortByKey(True, 3, keyfunc=lambda k: k.lower()).collect()
[('a', 3), ('fleece', 7), ('had', 2), ('lamb', 5),...('white', 9), ('whose', 6)]
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
memory = self._memory_limit()
serializer = self._jrdd_deserializer
def sortPartition(iterator):
sort = ExternalSorter(memory * 0.9, serializer).sorted
return iter(sort(iterator, key=lambda kv: keyfunc(kv[0]), reverse=(not ascending)))
if numPartitions == 1:
if self.getNumPartitions() > 1:
self = self.coalesce(1)
return self.mapPartitions(sortPartition, True)
# first compute the boundary of each part via sampling: we want to partition
# the key-space into bins such that the bins have roughly the same
# number of (key, value) pairs falling into them
rddSize = self.count()
if not rddSize:
return self # empty RDD
maxSampleSize = numPartitions * 20.0 # constant from Spark's RangePartitioner
fraction = min(maxSampleSize / max(rddSize, 1), 1.0)
samples = self.sample(False, fraction, 1).map(lambda kv: kv[0]).collect()
samples = sorted(samples, key=keyfunc)
# we have numPartitions many parts but one of the them has
# an implicit boundary
bounds = [samples[int(len(samples) * (i + 1) / numPartitions)]
for i in range(0, numPartitions - 1)]
def rangePartitioner(k):
p = bisect.bisect_left(bounds, keyfunc(k))
if ascending:
return p
else:
return numPartitions - 1 - p
return self.partitionBy(numPartitions, rangePartitioner).mapPartitions(sortPartition, True) |
Sorts this RDD by the given keyfunc
>>> tmp = [('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
>>> sc.parallelize(tmp).sortBy(lambda x: x[0]).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> sc.parallelize(tmp).sortBy(lambda x: x[1]).collect()
[('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)] | def sortBy(self, keyfunc, ascending=True, numPartitions=None):
"""
Sorts this RDD by the given keyfunc
>>> tmp = [('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
>>> sc.parallelize(tmp).sortBy(lambda x: x[0]).collect()
[('1', 3), ('2', 5), ('a', 1), ('b', 2), ('d', 4)]
>>> sc.parallelize(tmp).sortBy(lambda x: x[1]).collect()
[('a', 1), ('b', 2), ('1', 3), ('d', 4), ('2', 5)]
"""
return self.keyBy(keyfunc).sortByKey(ascending, numPartitions).values() |
Return the Cartesian product of this RDD and another one, that is, the
RDD of all pairs of elements C{(a, b)} where C{a} is in C{self} and
C{b} is in C{other}.
>>> rdd = sc.parallelize([1, 2])
>>> sorted(rdd.cartesian(rdd).collect())
[(1, 1), (1, 2), (2, 1), (2, 2)] | def cartesian(self, other):
"""
Return the Cartesian product of this RDD and another one, that is, the
RDD of all pairs of elements C{(a, b)} where C{a} is in C{self} and
C{b} is in C{other}.
>>> rdd = sc.parallelize([1, 2])
>>> sorted(rdd.cartesian(rdd).collect())
[(1, 1), (1, 2), (2, 1), (2, 2)]
"""
# Due to batching, we can't use the Java cartesian method.
deserializer = CartesianDeserializer(self._jrdd_deserializer,
other._jrdd_deserializer)
return RDD(self._jrdd.cartesian(other._jrdd), self.ctx, deserializer) |
Return an RDD of grouped items.
>>> rdd = sc.parallelize([1, 1, 2, 3, 5, 8])
>>> result = rdd.groupBy(lambda x: x % 2).collect()
>>> sorted([(x, sorted(y)) for (x, y) in result])
[(0, [2, 8]), (1, [1, 1, 3, 5])] | def groupBy(self, f, numPartitions=None, partitionFunc=portable_hash):
"""
Return an RDD of grouped items.
>>> rdd = sc.parallelize([1, 1, 2, 3, 5, 8])
>>> result = rdd.groupBy(lambda x: x % 2).collect()
>>> sorted([(x, sorted(y)) for (x, y) in result])
[(0, [2, 8]), (1, [1, 1, 3, 5])]
"""
return self.map(lambda x: (f(x), x)).groupByKey(numPartitions, partitionFunc) |
Return an RDD created by piping elements to a forked external process.
>>> sc.parallelize(['1', '2', '', '3']).pipe('cat').collect()
[u'1', u'2', u'', u'3']
:param checkCode: whether or not to check the return value of the shell command. | def pipe(self, command, env=None, checkCode=False):
"""
Return an RDD created by piping elements to a forked external process.
>>> sc.parallelize(['1', '2', '', '3']).pipe('cat').collect()
[u'1', u'2', u'', u'3']
:param checkCode: whether or not to check the return value of the shell command.
"""
if env is None:
env = dict()
def func(iterator):
pipe = Popen(
shlex.split(command), env=env, stdin=PIPE, stdout=PIPE)
def pipe_objs(out):
for obj in iterator:
s = unicode(obj).rstrip('\n') + '\n'
out.write(s.encode('utf-8'))
out.close()
Thread(target=pipe_objs, args=[pipe.stdin]).start()
def check_return_code():
pipe.wait()
if checkCode and pipe.returncode:
raise Exception("Pipe function `%s' exited "
"with error code %d" % (command, pipe.returncode))
else:
for i in range(0):
yield i
return (x.rstrip(b'\n').decode('utf-8') for x in
chain(iter(pipe.stdout.readline, b''), check_return_code()))
return self.mapPartitions(func) |
Applies a function to all elements of this RDD.
>>> def f(x): print(x)
>>> sc.parallelize([1, 2, 3, 4, 5]).foreach(f) | def foreach(self, f):
"""
Applies a function to all elements of this RDD.
>>> def f(x): print(x)
>>> sc.parallelize([1, 2, 3, 4, 5]).foreach(f)
"""
f = fail_on_stopiteration(f)
def processPartition(iterator):
for x in iterator:
f(x)
return iter([])
self.mapPartitions(processPartition).count() |
Applies a function to each partition of this RDD.
>>> def f(iterator):
... for x in iterator:
... print(x)
>>> sc.parallelize([1, 2, 3, 4, 5]).foreachPartition(f) | def foreachPartition(self, f):
"""
Applies a function to each partition of this RDD.
>>> def f(iterator):
... for x in iterator:
... print(x)
>>> sc.parallelize([1, 2, 3, 4, 5]).foreachPartition(f)
"""
def func(it):
r = f(it)
try:
return iter(r)
except TypeError:
return iter([])
self.mapPartitions(func).count() |
Return a list that contains all of the elements in this RDD.
.. note:: This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory. | def collect(self):
"""
Return a list that contains all of the elements in this RDD.
.. note:: This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
"""
with SCCallSiteSync(self.context) as css:
sock_info = self.ctx._jvm.PythonRDD.collectAndServe(self._jrdd.rdd())
return list(_load_from_socket(sock_info, self._jrdd_deserializer)) |
Reduces the elements of this RDD using the specified commutative and
associative binary operator. Currently reduces partitions locally.
>>> from operator import add
>>> sc.parallelize([1, 2, 3, 4, 5]).reduce(add)
15
>>> sc.parallelize((2 for _ in range(10))).map(lambda x: 1).cache().reduce(add)
10
>>> sc.parallelize([]).reduce(add)
Traceback (most recent call last):
...
ValueError: Can not reduce() empty RDD | def reduce(self, f):
"""
Reduces the elements of this RDD using the specified commutative and
associative binary operator. Currently reduces partitions locally.
>>> from operator import add
>>> sc.parallelize([1, 2, 3, 4, 5]).reduce(add)
15
>>> sc.parallelize((2 for _ in range(10))).map(lambda x: 1).cache().reduce(add)
10
>>> sc.parallelize([]).reduce(add)
Traceback (most recent call last):
...
ValueError: Can not reduce() empty RDD
"""
f = fail_on_stopiteration(f)
def func(iterator):
iterator = iter(iterator)
try:
initial = next(iterator)
except StopIteration:
return
yield reduce(f, iterator, initial)
vals = self.mapPartitions(func).collect()
if vals:
return reduce(f, vals)
raise ValueError("Can not reduce() empty RDD") |
Reduces the elements of this RDD in a multi-level tree pattern.
:param depth: suggested depth of the tree (default: 2)
>>> add = lambda x, y: x + y
>>> rdd = sc.parallelize([-5, -4, -3, -2, -1, 1, 2, 3, 4], 10)
>>> rdd.treeReduce(add)
-5
>>> rdd.treeReduce(add, 1)
-5
>>> rdd.treeReduce(add, 2)
-5
>>> rdd.treeReduce(add, 5)
-5
>>> rdd.treeReduce(add, 10)
-5 | def treeReduce(self, f, depth=2):
"""
Reduces the elements of this RDD in a multi-level tree pattern.
:param depth: suggested depth of the tree (default: 2)
>>> add = lambda x, y: x + y
>>> rdd = sc.parallelize([-5, -4, -3, -2, -1, 1, 2, 3, 4], 10)
>>> rdd.treeReduce(add)
-5
>>> rdd.treeReduce(add, 1)
-5
>>> rdd.treeReduce(add, 2)
-5
>>> rdd.treeReduce(add, 5)
-5
>>> rdd.treeReduce(add, 10)
-5
"""
if depth < 1:
raise ValueError("Depth cannot be smaller than 1 but got %d." % depth)
zeroValue = None, True # Use the second entry to indicate whether this is a dummy value.
def op(x, y):
if x[1]:
return y
elif y[1]:
return x
else:
return f(x[0], y[0]), False
reduced = self.map(lambda x: (x, False)).treeAggregate(zeroValue, op, op, depth)
if reduced[1]:
raise ValueError("Cannot reduce empty RDD.")
return reduced[0] |
Aggregate the elements of each partition, and then the results for all
the partitions, using a given associative function and a neutral "zero value."
The function C{op(t1, t2)} is allowed to modify C{t1} and return it
as its result value to avoid object allocation; however, it should not
modify C{t2}.
This behaves somewhat differently from fold operations implemented
for non-distributed collections in functional languages like Scala.
This fold operation may be applied to partitions individually, and then
fold those results into the final result, rather than apply the fold
to each element sequentially in some defined ordering. For functions
that are not commutative, the result may differ from that of a fold
applied to a non-distributed collection.
>>> from operator import add
>>> sc.parallelize([1, 2, 3, 4, 5]).fold(0, add)
15 | def fold(self, zeroValue, op):
"""
Aggregate the elements of each partition, and then the results for all
the partitions, using a given associative function and a neutral "zero value."
The function C{op(t1, t2)} is allowed to modify C{t1} and return it
as its result value to avoid object allocation; however, it should not
modify C{t2}.
This behaves somewhat differently from fold operations implemented
for non-distributed collections in functional languages like Scala.
This fold operation may be applied to partitions individually, and then
fold those results into the final result, rather than apply the fold
to each element sequentially in some defined ordering. For functions
that are not commutative, the result may differ from that of a fold
applied to a non-distributed collection.
>>> from operator import add
>>> sc.parallelize([1, 2, 3, 4, 5]).fold(0, add)
15
"""
op = fail_on_stopiteration(op)
def func(iterator):
acc = zeroValue
for obj in iterator:
acc = op(acc, obj)
yield acc
# collecting result of mapPartitions here ensures that the copy of
# zeroValue provided to each partition is unique from the one provided
# to the final reduce call
vals = self.mapPartitions(func).collect()
return reduce(op, vals, zeroValue) |
Aggregate the elements of each partition, and then the results for all
the partitions, using a given combine functions and a neutral "zero
value."
The functions C{op(t1, t2)} is allowed to modify C{t1} and return it
as its result value to avoid object allocation; however, it should not
modify C{t2}.
The first function (seqOp) can return a different result type, U, than
the type of this RDD. Thus, we need one operation for merging a T into
an U and one operation for merging two U
>>> seqOp = (lambda x, y: (x[0] + y, x[1] + 1))
>>> combOp = (lambda x, y: (x[0] + y[0], x[1] + y[1]))
>>> sc.parallelize([1, 2, 3, 4]).aggregate((0, 0), seqOp, combOp)
(10, 4)
>>> sc.parallelize([]).aggregate((0, 0), seqOp, combOp)
(0, 0) | def aggregate(self, zeroValue, seqOp, combOp):
"""
Aggregate the elements of each partition, and then the results for all
the partitions, using a given combine functions and a neutral "zero
value."
The functions C{op(t1, t2)} is allowed to modify C{t1} and return it
as its result value to avoid object allocation; however, it should not
modify C{t2}.
The first function (seqOp) can return a different result type, U, than
the type of this RDD. Thus, we need one operation for merging a T into
an U and one operation for merging two U
>>> seqOp = (lambda x, y: (x[0] + y, x[1] + 1))
>>> combOp = (lambda x, y: (x[0] + y[0], x[1] + y[1]))
>>> sc.parallelize([1, 2, 3, 4]).aggregate((0, 0), seqOp, combOp)
(10, 4)
>>> sc.parallelize([]).aggregate((0, 0), seqOp, combOp)
(0, 0)
"""
seqOp = fail_on_stopiteration(seqOp)
combOp = fail_on_stopiteration(combOp)
def func(iterator):
acc = zeroValue
for obj in iterator:
acc = seqOp(acc, obj)
yield acc
# collecting result of mapPartitions here ensures that the copy of
# zeroValue provided to each partition is unique from the one provided
# to the final reduce call
vals = self.mapPartitions(func).collect()
return reduce(combOp, vals, zeroValue) |
Aggregates the elements of this RDD in a multi-level tree
pattern.
:param depth: suggested depth of the tree (default: 2)
>>> add = lambda x, y: x + y
>>> rdd = sc.parallelize([-5, -4, -3, -2, -1, 1, 2, 3, 4], 10)
>>> rdd.treeAggregate(0, add, add)
-5
>>> rdd.treeAggregate(0, add, add, 1)
-5
>>> rdd.treeAggregate(0, add, add, 2)
-5
>>> rdd.treeAggregate(0, add, add, 5)
-5
>>> rdd.treeAggregate(0, add, add, 10)
-5 | def treeAggregate(self, zeroValue, seqOp, combOp, depth=2):
"""
Aggregates the elements of this RDD in a multi-level tree
pattern.
:param depth: suggested depth of the tree (default: 2)
>>> add = lambda x, y: x + y
>>> rdd = sc.parallelize([-5, -4, -3, -2, -1, 1, 2, 3, 4], 10)
>>> rdd.treeAggregate(0, add, add)
-5
>>> rdd.treeAggregate(0, add, add, 1)
-5
>>> rdd.treeAggregate(0, add, add, 2)
-5
>>> rdd.treeAggregate(0, add, add, 5)
-5
>>> rdd.treeAggregate(0, add, add, 10)
-5
"""
if depth < 1:
raise ValueError("Depth cannot be smaller than 1 but got %d." % depth)
if self.getNumPartitions() == 0:
return zeroValue
def aggregatePartition(iterator):
acc = zeroValue
for obj in iterator:
acc = seqOp(acc, obj)
yield acc
partiallyAggregated = self.mapPartitions(aggregatePartition)
numPartitions = partiallyAggregated.getNumPartitions()
scale = max(int(ceil(pow(numPartitions, 1.0 / depth))), 2)
# If creating an extra level doesn't help reduce the wall-clock time, we stop the tree
# aggregation.
while numPartitions > scale + numPartitions / scale:
numPartitions /= scale
curNumPartitions = int(numPartitions)
def mapPartition(i, iterator):
for obj in iterator:
yield (i % curNumPartitions, obj)
partiallyAggregated = partiallyAggregated \
.mapPartitionsWithIndex(mapPartition) \
.reduceByKey(combOp, curNumPartitions) \
.values()
return partiallyAggregated.reduce(combOp) |
Find the maximum item in this RDD.
:param key: A function used to generate key for comparing
>>> rdd = sc.parallelize([1.0, 5.0, 43.0, 10.0])
>>> rdd.max()
43.0
>>> rdd.max(key=str)
5.0 | def max(self, key=None):
"""
Find the maximum item in this RDD.
:param key: A function used to generate key for comparing
>>> rdd = sc.parallelize([1.0, 5.0, 43.0, 10.0])
>>> rdd.max()
43.0
>>> rdd.max(key=str)
5.0
"""
if key is None:
return self.reduce(max)
return self.reduce(lambda a, b: max(a, b, key=key)) |
Find the minimum item in this RDD.
:param key: A function used to generate key for comparing
>>> rdd = sc.parallelize([2.0, 5.0, 43.0, 10.0])
>>> rdd.min()
2.0
>>> rdd.min(key=str)
10.0 | def min(self, key=None):
"""
Find the minimum item in this RDD.
:param key: A function used to generate key for comparing
>>> rdd = sc.parallelize([2.0, 5.0, 43.0, 10.0])
>>> rdd.min()
2.0
>>> rdd.min(key=str)
10.0
"""
if key is None:
return self.reduce(min)
return self.reduce(lambda a, b: min(a, b, key=key)) |
Add up the elements in this RDD.
>>> sc.parallelize([1.0, 2.0, 3.0]).sum()
6.0 | def sum(self):
"""
Add up the elements in this RDD.
>>> sc.parallelize([1.0, 2.0, 3.0]).sum()
6.0
"""
return self.mapPartitions(lambda x: [sum(x)]).fold(0, operator.add) |
Return a L{StatCounter} object that captures the mean, variance
and count of the RDD's elements in one operation. | def stats(self):
"""
Return a L{StatCounter} object that captures the mean, variance
and count of the RDD's elements in one operation.
"""
def redFunc(left_counter, right_counter):
return left_counter.mergeStats(right_counter)
return self.mapPartitions(lambda i: [StatCounter(i)]).reduce(redFunc) |
Compute a histogram using the provided buckets. The buckets
are all open to the right except for the last which is closed.
e.g. [1,10,20,50] means the buckets are [1,10) [10,20) [20,50],
which means 1<=x<10, 10<=x<20, 20<=x<=50. And on the input of 1
and 50 we would have a histogram of 1,0,1.
If your histogram is evenly spaced (e.g. [0, 10, 20, 30]),
this can be switched from an O(log n) inseration to O(1) per
element (where n is the number of buckets).
Buckets must be sorted, not contain any duplicates, and have
at least two elements.
If `buckets` is a number, it will generate buckets which are
evenly spaced between the minimum and maximum of the RDD. For
example, if the min value is 0 and the max is 100, given `buckets`
as 2, the resulting buckets will be [0,50) [50,100]. `buckets` must
be at least 1. An exception is raised if the RDD contains infinity.
If the elements in the RDD do not vary (max == min), a single bucket
will be used.
The return value is a tuple of buckets and histogram.
>>> rdd = sc.parallelize(range(51))
>>> rdd.histogram(2)
([0, 25, 50], [25, 26])
>>> rdd.histogram([0, 5, 25, 50])
([0, 5, 25, 50], [5, 20, 26])
>>> rdd.histogram([0, 15, 30, 45, 60]) # evenly spaced buckets
([0, 15, 30, 45, 60], [15, 15, 15, 6])
>>> rdd = sc.parallelize(["ab", "ac", "b", "bd", "ef"])
>>> rdd.histogram(("a", "b", "c"))
(('a', 'b', 'c'), [2, 2]) | def histogram(self, buckets):
"""
Compute a histogram using the provided buckets. The buckets
are all open to the right except for the last which is closed.
e.g. [1,10,20,50] means the buckets are [1,10) [10,20) [20,50],
which means 1<=x<10, 10<=x<20, 20<=x<=50. And on the input of 1
and 50 we would have a histogram of 1,0,1.
If your histogram is evenly spaced (e.g. [0, 10, 20, 30]),
this can be switched from an O(log n) inseration to O(1) per
element (where n is the number of buckets).
Buckets must be sorted, not contain any duplicates, and have
at least two elements.
If `buckets` is a number, it will generate buckets which are
evenly spaced between the minimum and maximum of the RDD. For
example, if the min value is 0 and the max is 100, given `buckets`
as 2, the resulting buckets will be [0,50) [50,100]. `buckets` must
be at least 1. An exception is raised if the RDD contains infinity.
If the elements in the RDD do not vary (max == min), a single bucket
will be used.
The return value is a tuple of buckets and histogram.
>>> rdd = sc.parallelize(range(51))
>>> rdd.histogram(2)
([0, 25, 50], [25, 26])
>>> rdd.histogram([0, 5, 25, 50])
([0, 5, 25, 50], [5, 20, 26])
>>> rdd.histogram([0, 15, 30, 45, 60]) # evenly spaced buckets
([0, 15, 30, 45, 60], [15, 15, 15, 6])
>>> rdd = sc.parallelize(["ab", "ac", "b", "bd", "ef"])
>>> rdd.histogram(("a", "b", "c"))
(('a', 'b', 'c'), [2, 2])
"""
if isinstance(buckets, int):
if buckets < 1:
raise ValueError("number of buckets must be >= 1")
# filter out non-comparable elements
def comparable(x):
if x is None:
return False
if type(x) is float and isnan(x):
return False
return True
filtered = self.filter(comparable)
# faster than stats()
def minmax(a, b):
return min(a[0], b[0]), max(a[1], b[1])
try:
minv, maxv = filtered.map(lambda x: (x, x)).reduce(minmax)
except TypeError as e:
if " empty " in str(e):
raise ValueError("can not generate buckets from empty RDD")
raise
if minv == maxv or buckets == 1:
return [minv, maxv], [filtered.count()]
try:
inc = (maxv - minv) / buckets
except TypeError:
raise TypeError("Can not generate buckets with non-number in RDD")
if isinf(inc):
raise ValueError("Can not generate buckets with infinite value")
# keep them as integer if possible
inc = int(inc)
if inc * buckets != maxv - minv:
inc = (maxv - minv) * 1.0 / buckets
buckets = [i * inc + minv for i in range(buckets)]
buckets.append(maxv) # fix accumulated error
even = True
elif isinstance(buckets, (list, tuple)):
if len(buckets) < 2:
raise ValueError("buckets should have more than one value")
if any(i is None or isinstance(i, float) and isnan(i) for i in buckets):
raise ValueError("can not have None or NaN in buckets")
if sorted(buckets) != list(buckets):
raise ValueError("buckets should be sorted")
if len(set(buckets)) != len(buckets):
raise ValueError("buckets should not contain duplicated values")
minv = buckets[0]
maxv = buckets[-1]
even = False
inc = None
try:
steps = [buckets[i + 1] - buckets[i] for i in range(len(buckets) - 1)]
except TypeError:
pass # objects in buckets do not support '-'
else:
if max(steps) - min(steps) < 1e-10: # handle precision errors
even = True
inc = (maxv - minv) / (len(buckets) - 1)
else:
raise TypeError("buckets should be a list or tuple or number(int or long)")
def histogram(iterator):
counters = [0] * len(buckets)
for i in iterator:
if i is None or (type(i) is float and isnan(i)) or i > maxv or i < minv:
continue
t = (int((i - minv) / inc) if even
else bisect.bisect_right(buckets, i) - 1)
counters[t] += 1
# add last two together
last = counters.pop()
counters[-1] += last
return [counters]
def mergeCounters(a, b):
return [i + j for i, j in zip(a, b)]
return buckets, self.mapPartitions(histogram).reduce(mergeCounters) |
Return the count of each unique value in this RDD as a dictionary of
(value, count) pairs.
>>> sorted(sc.parallelize([1, 2, 1, 2, 2], 2).countByValue().items())
[(1, 2), (2, 3)] | def countByValue(self):
"""
Return the count of each unique value in this RDD as a dictionary of
(value, count) pairs.
>>> sorted(sc.parallelize([1, 2, 1, 2, 2], 2).countByValue().items())
[(1, 2), (2, 3)]
"""
def countPartition(iterator):
counts = defaultdict(int)
for obj in iterator:
counts[obj] += 1
yield counts
def mergeMaps(m1, m2):
for k, v in m2.items():
m1[k] += v
return m1
return self.mapPartitions(countPartition).reduce(mergeMaps) |
Get the top N elements from an RDD.
.. note:: This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
.. note:: It returns the list sorted in descending order.
>>> sc.parallelize([10, 4, 2, 12, 3]).top(1)
[12]
>>> sc.parallelize([2, 3, 4, 5, 6], 2).top(2)
[6, 5]
>>> sc.parallelize([10, 4, 2, 12, 3]).top(3, key=str)
[4, 3, 2] | def top(self, num, key=None):
"""
Get the top N elements from an RDD.
.. note:: This method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
.. note:: It returns the list sorted in descending order.
>>> sc.parallelize([10, 4, 2, 12, 3]).top(1)
[12]
>>> sc.parallelize([2, 3, 4, 5, 6], 2).top(2)
[6, 5]
>>> sc.parallelize([10, 4, 2, 12, 3]).top(3, key=str)
[4, 3, 2]
"""
def topIterator(iterator):
yield heapq.nlargest(num, iterator, key=key)
def merge(a, b):
return heapq.nlargest(num, a + b, key=key)
return self.mapPartitions(topIterator).reduce(merge) |
Get the N elements from an RDD ordered in ascending order or as
specified by the optional key function.
.. note:: this method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
>>> sc.parallelize([10, 1, 2, 9, 3, 4, 5, 6, 7]).takeOrdered(6)
[1, 2, 3, 4, 5, 6]
>>> sc.parallelize([10, 1, 2, 9, 3, 4, 5, 6, 7], 2).takeOrdered(6, key=lambda x: -x)
[10, 9, 7, 6, 5, 4] | def takeOrdered(self, num, key=None):
"""
Get the N elements from an RDD ordered in ascending order or as
specified by the optional key function.
.. note:: this method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
>>> sc.parallelize([10, 1, 2, 9, 3, 4, 5, 6, 7]).takeOrdered(6)
[1, 2, 3, 4, 5, 6]
>>> sc.parallelize([10, 1, 2, 9, 3, 4, 5, 6, 7], 2).takeOrdered(6, key=lambda x: -x)
[10, 9, 7, 6, 5, 4]
"""
def merge(a, b):
return heapq.nsmallest(num, a + b, key)
return self.mapPartitions(lambda it: [heapq.nsmallest(num, it, key)]).reduce(merge) |
Take the first num elements of the RDD.
It works by first scanning one partition, and use the results from
that partition to estimate the number of additional partitions needed
to satisfy the limit.
Translated from the Scala implementation in RDD#take().
.. note:: this method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
>>> sc.parallelize([2, 3, 4, 5, 6]).cache().take(2)
[2, 3]
>>> sc.parallelize([2, 3, 4, 5, 6]).take(10)
[2, 3, 4, 5, 6]
>>> sc.parallelize(range(100), 100).filter(lambda x: x > 90).take(3)
[91, 92, 93] | def take(self, num):
"""
Take the first num elements of the RDD.
It works by first scanning one partition, and use the results from
that partition to estimate the number of additional partitions needed
to satisfy the limit.
Translated from the Scala implementation in RDD#take().
.. note:: this method should only be used if the resulting array is expected
to be small, as all the data is loaded into the driver's memory.
>>> sc.parallelize([2, 3, 4, 5, 6]).cache().take(2)
[2, 3]
>>> sc.parallelize([2, 3, 4, 5, 6]).take(10)
[2, 3, 4, 5, 6]
>>> sc.parallelize(range(100), 100).filter(lambda x: x > 90).take(3)
[91, 92, 93]
"""
items = []
totalParts = self.getNumPartitions()
partsScanned = 0
while len(items) < num and partsScanned < totalParts:
# The number of partitions to try in this iteration.
# It is ok for this number to be greater than totalParts because
# we actually cap it at totalParts in runJob.
numPartsToTry = 1
if partsScanned > 0:
# If we didn't find any rows after the previous iteration,
# quadruple and retry. Otherwise, interpolate the number of
# partitions we need to try, but overestimate it by 50%.
# We also cap the estimation in the end.
if len(items) == 0:
numPartsToTry = partsScanned * 4
else:
# the first parameter of max is >=1 whenever partsScanned >= 2
numPartsToTry = int(1.5 * num * partsScanned / len(items)) - partsScanned
numPartsToTry = min(max(numPartsToTry, 1), partsScanned * 4)
left = num - len(items)
def takeUpToNumLeft(iterator):
iterator = iter(iterator)
taken = 0
while taken < left:
try:
yield next(iterator)
except StopIteration:
return
taken += 1
p = range(partsScanned, min(partsScanned + numPartsToTry, totalParts))
res = self.context.runJob(self, takeUpToNumLeft, p)
items += res
partsScanned += numPartsToTry
return items[:num] |
Output a Python RDD of key-value pairs (of form C{RDD[(K, V)]}) to any Hadoop file
system, using the new Hadoop OutputFormat API (mapreduce package). Keys/values are
converted for output using either user specified converters or, by default,
L{org.apache.spark.api.python.JavaToWritableConverter}.
:param conf: Hadoop job configuration, passed in as a dict
:param keyConverter: (None by default)
:param valueConverter: (None by default) | def saveAsNewAPIHadoopDataset(self, conf, keyConverter=None, valueConverter=None):
"""
Output a Python RDD of key-value pairs (of form C{RDD[(K, V)]}) to any Hadoop file
system, using the new Hadoop OutputFormat API (mapreduce package). Keys/values are
converted for output using either user specified converters or, by default,
L{org.apache.spark.api.python.JavaToWritableConverter}.
:param conf: Hadoop job configuration, passed in as a dict
:param keyConverter: (None by default)
:param valueConverter: (None by default)
"""
jconf = self.ctx._dictToJavaMap(conf)
pickledRDD = self._pickled()
self.ctx._jvm.PythonRDD.saveAsHadoopDataset(pickledRDD._jrdd, True, jconf,
keyConverter, valueConverter, True) |
Output a Python RDD of key-value pairs (of form C{RDD[(K, V)]}) to any Hadoop file
system, using the new Hadoop OutputFormat API (mapreduce package). Key and value types
will be inferred if not specified. Keys and values are converted for output using either
user specified converters or L{org.apache.spark.api.python.JavaToWritableConverter}. The
C{conf} is applied on top of the base Hadoop conf associated with the SparkContext
of this RDD to create a merged Hadoop MapReduce job configuration for saving the data.
:param path: path to Hadoop file
:param outputFormatClass: fully qualified classname of Hadoop OutputFormat
(e.g. "org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat")
:param keyClass: fully qualified classname of key Writable class
(e.g. "org.apache.hadoop.io.IntWritable", None by default)
:param valueClass: fully qualified classname of value Writable class
(e.g. "org.apache.hadoop.io.Text", None by default)
:param keyConverter: (None by default)
:param valueConverter: (None by default)
:param conf: Hadoop job configuration, passed in as a dict (None by default) | def saveAsNewAPIHadoopFile(self, path, outputFormatClass, keyClass=None, valueClass=None,
keyConverter=None, valueConverter=None, conf=None):
"""
Output a Python RDD of key-value pairs (of form C{RDD[(K, V)]}) to any Hadoop file
system, using the new Hadoop OutputFormat API (mapreduce package). Key and value types
will be inferred if not specified. Keys and values are converted for output using either
user specified converters or L{org.apache.spark.api.python.JavaToWritableConverter}. The
C{conf} is applied on top of the base Hadoop conf associated with the SparkContext
of this RDD to create a merged Hadoop MapReduce job configuration for saving the data.
:param path: path to Hadoop file
:param outputFormatClass: fully qualified classname of Hadoop OutputFormat
(e.g. "org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat")
:param keyClass: fully qualified classname of key Writable class
(e.g. "org.apache.hadoop.io.IntWritable", None by default)
:param valueClass: fully qualified classname of value Writable class
(e.g. "org.apache.hadoop.io.Text", None by default)
:param keyConverter: (None by default)
:param valueConverter: (None by default)
:param conf: Hadoop job configuration, passed in as a dict (None by default)
"""
jconf = self.ctx._dictToJavaMap(conf)
pickledRDD = self._pickled()
self.ctx._jvm.PythonRDD.saveAsNewAPIHadoopFile(pickledRDD._jrdd, True, path,
outputFormatClass,
keyClass, valueClass,
keyConverter, valueConverter, jconf) |
Output a Python RDD of key-value pairs (of form C{RDD[(K, V)]}) to any Hadoop file
system, using the L{org.apache.hadoop.io.Writable} types that we convert from the
RDD's key and value types. The mechanism is as follows:
1. Pyrolite is used to convert pickled Python RDD into RDD of Java objects.
2. Keys and values of this Java RDD are converted to Writables and written out.
:param path: path to sequence file
:param compressionCodecClass: (None by default) | def saveAsSequenceFile(self, path, compressionCodecClass=None):
"""
Output a Python RDD of key-value pairs (of form C{RDD[(K, V)]}) to any Hadoop file
system, using the L{org.apache.hadoop.io.Writable} types that we convert from the
RDD's key and value types. The mechanism is as follows:
1. Pyrolite is used to convert pickled Python RDD into RDD of Java objects.
2. Keys and values of this Java RDD are converted to Writables and written out.
:param path: path to sequence file
:param compressionCodecClass: (None by default)
"""
pickledRDD = self._pickled()
self.ctx._jvm.PythonRDD.saveAsSequenceFile(pickledRDD._jrdd, True,
path, compressionCodecClass) |
Save this RDD as a SequenceFile of serialized objects. The serializer
used is L{pyspark.serializers.PickleSerializer}, default batch size
is 10.
>>> tmpFile = NamedTemporaryFile(delete=True)
>>> tmpFile.close()
>>> sc.parallelize([1, 2, 'spark', 'rdd']).saveAsPickleFile(tmpFile.name, 3)
>>> sorted(sc.pickleFile(tmpFile.name, 5).map(str).collect())
['1', '2', 'rdd', 'spark'] | def saveAsPickleFile(self, path, batchSize=10):
"""
Save this RDD as a SequenceFile of serialized objects. The serializer
used is L{pyspark.serializers.PickleSerializer}, default batch size
is 10.
>>> tmpFile = NamedTemporaryFile(delete=True)
>>> tmpFile.close()
>>> sc.parallelize([1, 2, 'spark', 'rdd']).saveAsPickleFile(tmpFile.name, 3)
>>> sorted(sc.pickleFile(tmpFile.name, 5).map(str).collect())
['1', '2', 'rdd', 'spark']
"""
if batchSize == 0:
ser = AutoBatchedSerializer(PickleSerializer())
else:
ser = BatchedSerializer(PickleSerializer(), batchSize)
self._reserialize(ser)._jrdd.saveAsObjectFile(path) |
Save this RDD as a text file, using string representations of elements.
@param path: path to text file
@param compressionCodecClass: (None by default) string i.e.
"org.apache.hadoop.io.compress.GzipCodec"
>>> tempFile = NamedTemporaryFile(delete=True)
>>> tempFile.close()
>>> sc.parallelize(range(10)).saveAsTextFile(tempFile.name)
>>> from fileinput import input
>>> from glob import glob
>>> ''.join(sorted(input(glob(tempFile.name + "/part-0000*"))))
'0\\n1\\n2\\n3\\n4\\n5\\n6\\n7\\n8\\n9\\n'
Empty lines are tolerated when saving to text files.
>>> tempFile2 = NamedTemporaryFile(delete=True)
>>> tempFile2.close()
>>> sc.parallelize(['', 'foo', '', 'bar', '']).saveAsTextFile(tempFile2.name)
>>> ''.join(sorted(input(glob(tempFile2.name + "/part-0000*"))))
'\\n\\n\\nbar\\nfoo\\n'
Using compressionCodecClass
>>> tempFile3 = NamedTemporaryFile(delete=True)
>>> tempFile3.close()
>>> codec = "org.apache.hadoop.io.compress.GzipCodec"
>>> sc.parallelize(['foo', 'bar']).saveAsTextFile(tempFile3.name, codec)
>>> from fileinput import input, hook_compressed
>>> result = sorted(input(glob(tempFile3.name + "/part*.gz"), openhook=hook_compressed))
>>> b''.join(result).decode('utf-8')
u'bar\\nfoo\\n' | def saveAsTextFile(self, path, compressionCodecClass=None):
"""
Save this RDD as a text file, using string representations of elements.
@param path: path to text file
@param compressionCodecClass: (None by default) string i.e.
"org.apache.hadoop.io.compress.GzipCodec"
>>> tempFile = NamedTemporaryFile(delete=True)
>>> tempFile.close()
>>> sc.parallelize(range(10)).saveAsTextFile(tempFile.name)
>>> from fileinput import input
>>> from glob import glob
>>> ''.join(sorted(input(glob(tempFile.name + "/part-0000*"))))
'0\\n1\\n2\\n3\\n4\\n5\\n6\\n7\\n8\\n9\\n'
Empty lines are tolerated when saving to text files.
>>> tempFile2 = NamedTemporaryFile(delete=True)
>>> tempFile2.close()
>>> sc.parallelize(['', 'foo', '', 'bar', '']).saveAsTextFile(tempFile2.name)
>>> ''.join(sorted(input(glob(tempFile2.name + "/part-0000*"))))
'\\n\\n\\nbar\\nfoo\\n'
Using compressionCodecClass
>>> tempFile3 = NamedTemporaryFile(delete=True)
>>> tempFile3.close()
>>> codec = "org.apache.hadoop.io.compress.GzipCodec"
>>> sc.parallelize(['foo', 'bar']).saveAsTextFile(tempFile3.name, codec)
>>> from fileinput import input, hook_compressed
>>> result = sorted(input(glob(tempFile3.name + "/part*.gz"), openhook=hook_compressed))
>>> b''.join(result).decode('utf-8')
u'bar\\nfoo\\n'
"""
def func(split, iterator):
for x in iterator:
if not isinstance(x, (unicode, bytes)):
x = unicode(x)
if isinstance(x, unicode):
x = x.encode("utf-8")
yield x
keyed = self.mapPartitionsWithIndex(func)
keyed._bypass_serializer = True
if compressionCodecClass:
compressionCodec = self.ctx._jvm.java.lang.Class.forName(compressionCodecClass)
keyed._jrdd.map(self.ctx._jvm.BytesToString()).saveAsTextFile(path, compressionCodec)
else:
keyed._jrdd.map(self.ctx._jvm.BytesToString()).saveAsTextFile(path) |
Merge the values for each key using an associative and commutative reduce function.
This will also perform the merging locally on each mapper before
sending results to a reducer, similarly to a "combiner" in MapReduce.
Output will be partitioned with C{numPartitions} partitions, or
the default parallelism level if C{numPartitions} is not specified.
Default partitioner is hash-partition.
>>> from operator import add
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.reduceByKey(add).collect())
[('a', 2), ('b', 1)] | def reduceByKey(self, func, numPartitions=None, partitionFunc=portable_hash):
"""
Merge the values for each key using an associative and commutative reduce function.
This will also perform the merging locally on each mapper before
sending results to a reducer, similarly to a "combiner" in MapReduce.
Output will be partitioned with C{numPartitions} partitions, or
the default parallelism level if C{numPartitions} is not specified.
Default partitioner is hash-partition.
>>> from operator import add
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.reduceByKey(add).collect())
[('a', 2), ('b', 1)]
"""
return self.combineByKey(lambda x: x, func, func, numPartitions, partitionFunc) |
Merge the values for each key using an associative and commutative reduce function, but
return the results immediately to the master as a dictionary.
This will also perform the merging locally on each mapper before
sending results to a reducer, similarly to a "combiner" in MapReduce.
>>> from operator import add
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.reduceByKeyLocally(add).items())
[('a', 2), ('b', 1)] | def reduceByKeyLocally(self, func):
"""
Merge the values for each key using an associative and commutative reduce function, but
return the results immediately to the master as a dictionary.
This will also perform the merging locally on each mapper before
sending results to a reducer, similarly to a "combiner" in MapReduce.
>>> from operator import add
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> sorted(rdd.reduceByKeyLocally(add).items())
[('a', 2), ('b', 1)]
"""
func = fail_on_stopiteration(func)
def reducePartition(iterator):
m = {}
for k, v in iterator:
m[k] = func(m[k], v) if k in m else v
yield m
def mergeMaps(m1, m2):
for k, v in m2.items():
m1[k] = func(m1[k], v) if k in m1 else v
return m1
return self.mapPartitions(reducePartition).reduce(mergeMaps) |
Return a copy of the RDD partitioned using the specified partitioner.
>>> pairs = sc.parallelize([1, 2, 3, 4, 2, 4, 1]).map(lambda x: (x, x))
>>> sets = pairs.partitionBy(2).glom().collect()
>>> len(set(sets[0]).intersection(set(sets[1])))
0 | def partitionBy(self, numPartitions, partitionFunc=portable_hash):
"""
Return a copy of the RDD partitioned using the specified partitioner.
>>> pairs = sc.parallelize([1, 2, 3, 4, 2, 4, 1]).map(lambda x: (x, x))
>>> sets = pairs.partitionBy(2).glom().collect()
>>> len(set(sets[0]).intersection(set(sets[1])))
0
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
partitioner = Partitioner(numPartitions, partitionFunc)
if self.partitioner == partitioner:
return self
# Transferring O(n) objects to Java is too expensive.
# Instead, we'll form the hash buckets in Python,
# transferring O(numPartitions) objects to Java.
# Each object is a (splitNumber, [objects]) pair.
# In order to avoid too huge objects, the objects are
# grouped into chunks.
outputSerializer = self.ctx._unbatched_serializer
limit = (_parse_memory(self.ctx._conf.get(
"spark.python.worker.memory", "512m")) / 2)
def add_shuffle_key(split, iterator):
buckets = defaultdict(list)
c, batch = 0, min(10 * numPartitions, 1000)
for k, v in iterator:
buckets[partitionFunc(k) % numPartitions].append((k, v))
c += 1
# check used memory and avg size of chunk of objects
if (c % 1000 == 0 and get_used_memory() > limit
or c > batch):
n, size = len(buckets), 0
for split in list(buckets.keys()):
yield pack_long(split)
d = outputSerializer.dumps(buckets[split])
del buckets[split]
yield d
size += len(d)
avg = int(size / n) >> 20
# let 1M < avg < 10M
if avg < 1:
batch *= 1.5
elif avg > 10:
batch = max(int(batch / 1.5), 1)
c = 0
for split, items in buckets.items():
yield pack_long(split)
yield outputSerializer.dumps(items)
keyed = self.mapPartitionsWithIndex(add_shuffle_key, preservesPartitioning=True)
keyed._bypass_serializer = True
with SCCallSiteSync(self.context) as css:
pairRDD = self.ctx._jvm.PairwiseRDD(
keyed._jrdd.rdd()).asJavaPairRDD()
jpartitioner = self.ctx._jvm.PythonPartitioner(numPartitions,
id(partitionFunc))
jrdd = self.ctx._jvm.PythonRDD.valueOfPair(pairRDD.partitionBy(jpartitioner))
rdd = RDD(jrdd, self.ctx, BatchedSerializer(outputSerializer))
rdd.partitioner = partitioner
return rdd |
Generic function to combine the elements for each key using a custom
set of aggregation functions.
Turns an RDD[(K, V)] into a result of type RDD[(K, C)], for a "combined
type" C.
Users provide three functions:
- C{createCombiner}, which turns a V into a C (e.g., creates
a one-element list)
- C{mergeValue}, to merge a V into a C (e.g., adds it to the end of
a list)
- C{mergeCombiners}, to combine two C's into a single one (e.g., merges
the lists)
To avoid memory allocation, both mergeValue and mergeCombiners are allowed to
modify and return their first argument instead of creating a new C.
In addition, users can control the partitioning of the output RDD.
.. note:: V and C can be different -- for example, one might group an RDD of type
(Int, Int) into an RDD of type (Int, List[Int]).
>>> x = sc.parallelize([("a", 1), ("b", 1), ("a", 2)])
>>> def to_list(a):
... return [a]
...
>>> def append(a, b):
... a.append(b)
... return a
...
>>> def extend(a, b):
... a.extend(b)
... return a
...
>>> sorted(x.combineByKey(to_list, append, extend).collect())
[('a', [1, 2]), ('b', [1])] | def combineByKey(self, createCombiner, mergeValue, mergeCombiners,
numPartitions=None, partitionFunc=portable_hash):
"""
Generic function to combine the elements for each key using a custom
set of aggregation functions.
Turns an RDD[(K, V)] into a result of type RDD[(K, C)], for a "combined
type" C.
Users provide three functions:
- C{createCombiner}, which turns a V into a C (e.g., creates
a one-element list)
- C{mergeValue}, to merge a V into a C (e.g., adds it to the end of
a list)
- C{mergeCombiners}, to combine two C's into a single one (e.g., merges
the lists)
To avoid memory allocation, both mergeValue and mergeCombiners are allowed to
modify and return their first argument instead of creating a new C.
In addition, users can control the partitioning of the output RDD.
.. note:: V and C can be different -- for example, one might group an RDD of type
(Int, Int) into an RDD of type (Int, List[Int]).
>>> x = sc.parallelize([("a", 1), ("b", 1), ("a", 2)])
>>> def to_list(a):
... return [a]
...
>>> def append(a, b):
... a.append(b)
... return a
...
>>> def extend(a, b):
... a.extend(b)
... return a
...
>>> sorted(x.combineByKey(to_list, append, extend).collect())
[('a', [1, 2]), ('b', [1])]
"""
if numPartitions is None:
numPartitions = self._defaultReducePartitions()
serializer = self.ctx.serializer
memory = self._memory_limit()
agg = Aggregator(createCombiner, mergeValue, mergeCombiners)
def combineLocally(iterator):
merger = ExternalMerger(agg, memory * 0.9, serializer)
merger.mergeValues(iterator)
return merger.items()
locally_combined = self.mapPartitions(combineLocally, preservesPartitioning=True)
shuffled = locally_combined.partitionBy(numPartitions, partitionFunc)
def _mergeCombiners(iterator):
merger = ExternalMerger(agg, memory, serializer)
merger.mergeCombiners(iterator)
return merger.items()
return shuffled.mapPartitions(_mergeCombiners, preservesPartitioning=True) |
Aggregate the values of each key, using given combine functions and a neutral
"zero value". This function can return a different result type, U, than the type
of the values in this RDD, V. Thus, we need one operation for merging a V into
a U and one operation for merging two U's, The former operation is used for merging
values within a partition, and the latter is used for merging values between
partitions. To avoid memory allocation, both of these functions are
allowed to modify and return their first argument instead of creating a new U. | def aggregateByKey(self, zeroValue, seqFunc, combFunc, numPartitions=None,
partitionFunc=portable_hash):
"""
Aggregate the values of each key, using given combine functions and a neutral
"zero value". This function can return a different result type, U, than the type
of the values in this RDD, V. Thus, we need one operation for merging a V into
a U and one operation for merging two U's, The former operation is used for merging
values within a partition, and the latter is used for merging values between
partitions. To avoid memory allocation, both of these functions are
allowed to modify and return their first argument instead of creating a new U.
"""
def createZero():
return copy.deepcopy(zeroValue)
return self.combineByKey(
lambda v: seqFunc(createZero(), v), seqFunc, combFunc, numPartitions, partitionFunc) |
Merge the values for each key using an associative function "func"
and a neutral "zeroValue" which may be added to the result an
arbitrary number of times, and must not change the result
(e.g., 0 for addition, or 1 for multiplication.).
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> from operator import add
>>> sorted(rdd.foldByKey(0, add).collect())
[('a', 2), ('b', 1)] | def foldByKey(self, zeroValue, func, numPartitions=None, partitionFunc=portable_hash):
"""
Merge the values for each key using an associative function "func"
and a neutral "zeroValue" which may be added to the result an
arbitrary number of times, and must not change the result
(e.g., 0 for addition, or 1 for multiplication.).
>>> rdd = sc.parallelize([("a", 1), ("b", 1), ("a", 1)])
>>> from operator import add
>>> sorted(rdd.foldByKey(0, add).collect())
[('a', 2), ('b', 1)]
"""
def createZero():
return copy.deepcopy(zeroValue)
return self.combineByKey(lambda v: func(createZero(), v), func, func, numPartitions,
partitionFunc) |
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