File size: 4,828 Bytes
9c6594c |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 |
import os.path
from pathlib import Path
from typing import Any, Callable, Optional, Tuple, Union
import numpy as np
from PIL import Image
from .utils import check_integrity, download_url, verify_str_arg
from .vision import VisionDataset
class SVHN(VisionDataset):
"""`SVHN <http://ufldl.stanford.edu/housenumbers/>`_ Dataset.
Note: The SVHN dataset assigns the label `10` to the digit `0`. However, in this Dataset,
we assign the label `0` to the digit `0` to be compatible with PyTorch loss functions which
expect the class labels to be in the range `[0, C-1]`
.. warning::
This class needs `scipy <https://docs.scipy.org/doc/>`_ to load data from `.mat` format.
Args:
root (str or ``pathlib.Path``): Root directory of the dataset where the data is stored.
split (string): One of {'train', 'test', 'extra'}.
Accordingly dataset is selected. 'extra' is Extra training set.
transform (callable, optional): A function/transform that takes in a PIL image
and returns a transformed version. E.g, ``transforms.RandomCrop``
target_transform (callable, optional): A function/transform that takes in the
target and transforms it.
download (bool, optional): If true, downloads the dataset from the internet and
puts it in root directory. If dataset is already downloaded, it is not
downloaded again.
"""
split_list = {
"train": [
"http://ufldl.stanford.edu/housenumbers/train_32x32.mat",
"train_32x32.mat",
"e26dedcc434d2e4c54c9b2d4a06d8373",
],
"test": [
"http://ufldl.stanford.edu/housenumbers/test_32x32.mat",
"test_32x32.mat",
"eb5a983be6a315427106f1b164d9cef3",
],
"extra": [
"http://ufldl.stanford.edu/housenumbers/extra_32x32.mat",
"extra_32x32.mat",
"a93ce644f1a588dc4d68dda5feec44a7",
],
}
def __init__(
self,
root: Union[str, Path],
split: str = "train",
transform: Optional[Callable] = None,
target_transform: Optional[Callable] = None,
download: bool = False,
) -> None:
super().__init__(root, transform=transform, target_transform=target_transform)
self.split = verify_str_arg(split, "split", tuple(self.split_list.keys()))
self.url = self.split_list[split][0]
self.filename = self.split_list[split][1]
self.file_md5 = self.split_list[split][2]
if download:
self.download()
if not self._check_integrity():
raise RuntimeError("Dataset not found or corrupted. You can use download=True to download it")
# import here rather than at top of file because this is
# an optional dependency for torchvision
import scipy.io as sio
# reading(loading) mat file as array
loaded_mat = sio.loadmat(os.path.join(self.root, self.filename))
self.data = loaded_mat["X"]
# loading from the .mat file gives an np.ndarray of type np.uint8
# converting to np.int64, so that we have a LongTensor after
# the conversion from the numpy array
# the squeeze is needed to obtain a 1D tensor
self.labels = loaded_mat["y"].astype(np.int64).squeeze()
# the svhn dataset assigns the class label "10" to the digit 0
# this makes it inconsistent with several loss functions
# which expect the class labels to be in the range [0, C-1]
np.place(self.labels, self.labels == 10, 0)
self.data = np.transpose(self.data, (3, 2, 0, 1))
def __getitem__(self, index: int) -> Tuple[Any, Any]:
"""
Args:
index (int): Index
Returns:
tuple: (image, target) where target is index of the target class.
"""
img, target = self.data[index], int(self.labels[index])
# doing this so that it is consistent with all other datasets
# to return a PIL Image
img = Image.fromarray(np.transpose(img, (1, 2, 0)))
if self.transform is not None:
img = self.transform(img)
if self.target_transform is not None:
target = self.target_transform(target)
return img, target
def __len__(self) -> int:
return len(self.data)
def _check_integrity(self) -> bool:
root = self.root
md5 = self.split_list[self.split][2]
fpath = os.path.join(root, self.filename)
return check_integrity(fpath, md5)
def download(self) -> None:
md5 = self.split_list[self.split][2]
download_url(self.url, self.root, self.filename, md5)
def extra_repr(self) -> str:
return "Split: {split}".format(**self.__dict__)
|