Support for streaming

Use "virtual-hosted–style" access to download images and metadata;
allowing the Hugging Face download manager to operate in either
regular or streaming mode.

pest-management-opendata.py

@@ -4,9 +4,6 @@ from pathlib import Path
 from dataclasses import dataclass, asdict
 from urllib.parse import urlparse, urlunparse
 
-import cv2
-import boto3
-import numpy as np
 import pandas as pd
 import awswrangler as wr
 from datasets import (
@@ -25,19 +22,55 @@ from shapely.wkt import loads
 __version__ = '20220912-2056'
 
 SplitInfo = cl.namedtuple('SplitInfo', 'dtype, basename, split')
+Payload = cl.namedtuple('Payload', 'source, target, df')
+
+def readsp(path, split):
+    return (pd
+            .read_csv(path, compression='gzip')
+            .query(f'split == "{split}"'))
 
 @dataclass
 class SplitPayload:
     split: str
-    path: Path
+    metadata: Path
+    images: dict
+
+    def __iter__(self):
+        df = readsp(self.metadata, self.split)
+        for (i, g) in df.groupby('url', sort=False):
+            source = urlparse(i)
+            target = Path(self.images[i])
+
+            yield Payload(source, target, g)
+
+#
+#
+#
+class AmazonStorageStyleAccess:
+    def __init__(self, url):
+        self.url = url
+
+    def __str__(self):
+        return urlunparse(self.url)
+
+class StandardStyleAccess(AmazonStorageStyleAccess):
+    pass
 
-    def __post_init__(self):
-        self.path = Path(self.path)
+class VirtualStyleAccess(AmazonStorageStyleAccess):
+    _region = 'ap-south-1'
 
-    def to_frame(self):
-        return (pd
-                .read_csv(self.path, compression='gzip')
-                .query(f'split == "{self.split}"'))
+    def __init__(self, url):
+        parts = [
+            url.netloc,
+            url.scheme,
+            self._region,
+            'amazonaws',
+            'com',
+        ]
+        netloc = '.'.join(parts)
+        url = url._replace(scheme='https', netloc=netloc)
+
+        super().__init__(url)
 
 #
 #
@@ -49,20 +82,10 @@ class SplitManager:
         (Split.TEST, 'test', 'test'),
     )))
 
-    @staticmethod
-    def custom_download(url, path):
-        remote = urlparse(url)
-        name = Path(remote.path)
-        if name.is_absolute():
-            name = name.relative_to(name.parents[-1])
-
-        s3 = boto3.client(remote.scheme)
-        s3.download_file(remote.netloc, str(name), path)
-
     @property
     def labels(self):
-        path = self.url('dev')
-        df = wr.s3.read_csv(path, compression='gzip')
+        path = StandardStyleAccess(self.metaname('dev'))
+        df = wr.s3.read_csv(str(path), compression='gzip')
         yield from df['label'].dropna().unique()
 
     def __init__(self, bucket):
@@ -71,22 +94,31 @@ class SplitManager:
 
     def __call__(self, dl_manager):
         for i in self._splits:
-            url = self.url(i.basename)
-            path = dl_manager.download_custom(url, self.custom_download)
-            payload = SplitPayload(i.split, path)
+            name = self.metaname(i.basename)
+            url = VirtualStyleAccess(name)
+            info = Path(dl_manager.download(str(url)))
+
+            images = self.images(i.split, info)
+            ipaths = dl_manager.download(dict(images))
 
+            payload = SplitPayload(i.split, info, ipaths)
             yield SplitGenerator(name=i.dtype, gen_kwargs=asdict(payload))
 
-    def url(self, split):
+    @staticmethod
+    def images(split, info):
+        df = readsp(info, split)
+        for i in df['url'].unique():
+            url = VirtualStyleAccess(urlparse(i))
+            yield (i, str(url))
+
+    def metaname(self, split):
         path = self.path.joinpath(split).with_suffix('.csv.gz')
-        source = self.bucket._replace(path=str(path))
-        return urlunparse(source)
+        return self.bucket._replace(path=str(path))
 
 #
 #
 #
 class ExampleManager:
-    _decode_flags = cv2.IMREAD_COLOR | cv2.IMREAD_IGNORE_ORIENTATION
     # _Pest = cl.namedtuple('_Pest', 'label, geometry')
     # _Feature = cl.namedtuple('_Feature', 'image, pests')
 
@@ -114,31 +146,19 @@ class ExampleManager:
         self.payload = payload
 
     def __iter__(self):
-        df = self.payload.to_frame()
-        for (i, g) in df.groupby('url', sort=False):
+        for i in self.payload:
+            key = urlunparse(i.source)
+            with i.target.open('rb') as fp:
+                raw = fp.read()
             value = {
-                'image': self.load(urlparse(i)),
-                'pests': list(self.pests(g)),
+                'image': {
+                    'path': i.target,
+                    'bytes': raw,
+                },
+                'pests': list(self.pests(i.df)),
             }
 
-            yield (i, value)
-
-    def load(self, url):
-        path = Path(url.path)
-        if path.is_absolute():
-            (*_, root) = path.parents
-            path = path.relative_to(root)
-
-        data = (boto3
-                .resource(url.scheme)
-                .Bucket(url.netloc)
-                .Object(str(path))
-                .get()
-                .get('Body')
-                .read())
-        image = np.asarray(bytearray(data))
-
-        return cv2.imdecode(image, self._decode_flags)
+            yield (key, value)
 
 #
 #