Migrate docstrings to doctests (#901)

Summary:
### Changes
Migrate docstrings to doctest
- torchdata/dataloader2/adapter.py
- torchdata/datapipes/iter/load/*

Use PEP8 style in code examples, e.g. add newlines between defs:
```
  from torchdata.datapipes.iter import IterableWrapper

  def filepath_fn(name: str) -> str:
      return dir_path + name

  name_to_data = {"1.txt": b"DATA1", "2.txt": b"DATA2", "3.txt": b"DATA3"}
  source_dp = IterableWrapper(sorted(name_to_data.items()))
  fsspec_saver_dp = source_dp.save_by_fsspec(filepath_fn=filepath_fn, mode="wb")
  res_file_paths = list(fsspec_saver_dp)`
```

Pull Request resolved: #901

Reviewed By: bdhirsh

Differential Revision: D44518888

Pulled By: NivekT

fbshipit-source-id: 787a91c4b83a73140c83c198e5c24c82407a5fdb

Author: Mathias Burger

torchdata/dataloader2/adapter.py

@@ -67,7 +67,6 @@ class Shuffle(Adapter):
         dp = IterableWrapper(range(size)).shuffle()
         dl = DataLoader2(dp, [Shuffle(False)])
         assert list(range(size)) == list(dl)
-
     """
 
     def __init__(self, enable=True):
@@ -86,7 +85,19 @@ class CacheTimeout(Adapter):
         timeout: int - amount of seconds parallel processes will wait for cached files to appear.
 
     Example:
-        >>>  dl = DataLoader2(dp, [CacheTimeout(600)])
+
+    .. testsetup::
+
+        from torchdata.datapipes.iter import IterableWrapper
+        from torchdata.dataloader2 import DataLoader2
+        from torchdata.dataloader2.adapter import CacheTimeout
+
+        size = 12
+
+    .. testcode::
+
+        dp = IterableWrapper(range(size)).shuffle()
+        dl = DataLoader2(dp, [CacheTimeout(600)])
     """
 
     def __init__(self, timeout=None):

torchdata/datapipes/iter/load/fsspec.py

@@ -47,8 +47,16 @@ class FSSpecFileListerIterDataPipe(IterDataPipe[str]):
             e.g. host, port, username, password, etc.
 
     Example:
-        >>> from torchdata.datapipes.iter import FSSpecFileLister
-        >>> datapipe = FSSpecFileLister(root=dir_path)
+
+    .. testsetup::
+
+        dir_path = "path"
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import FSSpecFileLister
+
+        datapipe = FSSpecFileLister(root=dir_path)
     """
 
     def __init__(
@@ -127,9 +135,17 @@ class FSSpecFileOpenerIterDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
             e.g. host, port, username, password, etc.
 
     Example:
-        >>> from torchdata.datapipes.iter import FSSpecFileLister
-        >>> datapipe = FSSpecFileLister(root=dir_path)
-        >>> file_dp = datapipe.open_files_by_fsspec()
+
+    .. testsetup::
+
+        dir_path = "path"
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import FSSpecFileLister
+
+        datapipe = FSSpecFileLister(root=dir_path)
+        file_dp = datapipe.open_files_by_fsspec()
     """
 
     def __init__(
@@ -169,13 +185,31 @@ class FSSpecSaverIterDataPipe(IterDataPipe[str]):
 
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper
-        >>> def filepath_fn(name: str) -> str:
-        >>>     return dir_path + name
-        >>> name_to_data = {"1.txt": b"DATA1", "2.txt": b"DATA2", "3.txt": b"DATA3"}
-        >>> source_dp = IterableWrapper(sorted(name_to_data.items()))
-        >>> fsspec_saver_dp = source_dp.save_by_fsspec(filepath_fn=filepath_fn, mode="wb")
-        >>> res_file_paths = list(fsspec_saver_dp)
+
+    .. testsetup::
+
+        file_prefix = "file"
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper
+
+
+        def filepath_fn(name: str) -> str:
+            return file_prefix + name
+
+
+        name_to_data = {"1.txt": b"DATA1", "2.txt": b"DATA2", "3.txt": b"DATA3"}
+        source_dp = IterableWrapper(sorted(name_to_data.items()))
+        fsspec_saver_dp = source_dp.save_by_fsspec(filepath_fn=filepath_fn, mode="wb")
+        res_file_paths = list(fsspec_saver_dp)
+
+    .. testcleanup::
+
+        import os
+
+        for name in name_to_data.keys():
+            os.remove(file_prefix + name)
     """
 
     def __init__(

torchdata/datapipes/iter/load/iopath.py

@@ -55,8 +55,16 @@ class IoPathFileListerIterDataPipe(IterDataPipe[str]):
         S3 URL is supported only with ``iopath``>=0.1.9.
 
     Example:
-        >>> from torchdata.datapipes.iter import IoPathFileLister
-        >>> datapipe = IoPathFileLister(root=S3URL)
+
+    .. testsetup::
+
+        s3_url = "path"
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IoPathFileLister
+
+        datapipe = IoPathFileLister(root=s3_url)
     """
 
     def __init__(
@@ -113,9 +121,17 @@ class IoPathFileOpenerIterDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
         S3 URL is supported only with `iopath`>=0.1.9.
 
     Example:
-        >>> from torchdata.datapipes.iter import IoPathFileLister
-        >>> datapipe = IoPathFileLister(root=S3URL)
-        >>> file_dp = datapipe.open_files_by_iopath()
+
+    .. testsetup::
+
+        s3_url = "path"
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IoPathFileLister
+
+        datapipe = IoPathFileLister(root=s3_url)
+        file_dp = datapipe.open_files_by_iopath()
     """
 
     def __init__(self, source_datapipe: IterDataPipe[str], mode: str = "r", pathmgr=None) -> None:
@@ -161,13 +177,31 @@ class IoPathSaverIterDataPipe(IterDataPipe[str]):
         S3 URL is supported only with `iopath`>=0.1.9.
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper
-        >>> def filepath_fn(name: str) -> str:
-        >>>     return S3URL + name
-        >>> name_to_data = {"1.txt": b"DATA1", "2.txt": b"DATA2", "3.txt": b"DATA3"}
-        >>> source_dp = IterableWrapper(sorted(name_to_data.items()))
-        >>> iopath_saver_dp = source_dp.save_by_iopath(filepath_fn=filepath_fn, mode="wb")
-        >>> res_file_paths = list(iopath_saver_dp)
+
+    .. testsetup::
+
+        s3_url = "url"
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper
+
+
+        def filepath_fn(name: str) -> str:
+            return s3_url + name
+
+
+        name_to_data = {"1.txt": b"DATA1", "2.txt": b"DATA2", "3.txt": b"DATA3"}
+        source_dp = IterableWrapper(sorted(name_to_data.items()))
+        iopath_saver_dp = source_dp.save_by_iopath(filepath_fn=filepath_fn, mode="wb")
+        res_file_paths = list(iopath_saver_dp)
+
+    .. testcleanup::
+
+        import os
+
+        for file in ["1.txt", "1.txt.lock", "2.txt", "2.txt.lock", "3.txt", "3.txt.lock"]:
+            os.remove(s3_url + file)
     """
 
     def __init__(

torchdata/datapipes/iter/load/online.py

@@ -54,18 +54,25 @@ class HTTPReaderIterDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
         **kwargs: a Dictionary to pass optional arguments that requests takes. For the full list check out https://docs.python-requests.org/en/master/api/
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper, HttpReader
-        >>> file_url = "https://raw.githubusercontent.com/pytorch/data/main/LICENSE"
-        >>> query_params = {"auth" : ("fake_username", "fake_password"), "allow_redirects" : True}
-        >>> timeout = 120
-        >>> http_reader_dp = HttpReader(IterableWrapper([file_url]), timeout=timeout, query_params)
-        >>> reader_dp = http_reader_dp.readlines()
-        >>> it = iter(reader_dp)
-        >>> path, line = next(it)
-        >>> path
-        https://raw.githubusercontent.com/pytorch/data/main/LICENSE
-        >>> line
-        b'BSD 3-Clause License'
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper, HttpReader
+
+        file_url = "https://raw.githubusercontent.com/pytorch/data/main/LICENSE"
+        query_params = {"auth" : ("fake_username", "fake_password"), "allow_redirects" : True}
+        timeout = 120
+        http_reader_dp = HttpReader(IterableWrapper([file_url]), timeout=timeout, **query_params)
+        reader_dp = http_reader_dp.readlines()
+        it = iter(reader_dp)
+        path, line = next(it)
+        print((path, line))
+
+    Output:
+
+    .. testoutput::
+
+        ('https://raw.githubusercontent.com/pytorch/data/main/LICENSE', b'BSD 3-Clause License')
     """
 
     def __init__(
@@ -154,16 +161,31 @@ class GDriveReaderDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
         **kwargs: a Dictionary to pass optional arguments that requests takes. For the full list check out https://docs.python-requests.org/en/master/api/
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper, GDriveReader
-        >>> gdrive_file_url = "https://drive.google.com/uc?export=download&id=SomeIDToAGDriveFile"
-        >>> gdrive_reader_dp = GDriveReader(IterableWrapper([gdrive_file_url]))
-        >>> reader_dp = gdrive_reader_dp.readlines()
-        >>> it = iter(reader_dp)
-        >>> path, line = next(it)
-        >>> path
-        https://drive.google.com/uc?export=download&id=SomeIDToAGDriveFile
-        >>> line
-        <First line from the GDrive File>
+
+    .. testsetup::
+
+        from torchdata.datapipes.iter import GDriveReader
+
+        GDriveReader.readlines = lambda self: [
+            ("https://drive.google.com/uc?export=download&id=SomeIDToAGDriveFile", b"<First line from the GDrive File>")
+        ]
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper, GDriveReader
+
+        gdrive_file_url = "https://drive.google.com/uc?export=download&id=SomeIDToAGDriveFile"
+        gdrive_reader_dp = GDriveReader(IterableWrapper([gdrive_file_url]))
+        reader_dp = gdrive_reader_dp.readlines()
+        it = iter(reader_dp)
+        path, line = next(it)
+        print((path, line))
+
+    Output:
+
+    .. testoutput::
+
+        ('https://drive.google.com/uc?export=download&id=SomeIDToAGDriveFile', b'<First line from the GDrive File>')
     """
     source_datapipe: IterDataPipe[str]
 
@@ -207,16 +229,23 @@ class OnlineReaderIterDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
         **kwargs: a Dictionary to pass optional arguments that requests takes. For the full list check out https://docs.python-requests.org/en/master/api/
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper, OnlineReader
-        >>> file_url = "https://raw.githubusercontent.com/pytorch/data/main/LICENSE"
-        >>> online_reader_dp = OnlineReader(IterableWrapper([file_url]))
-        >>> reader_dp = online_reader_dp.readlines()
-        >>> it = iter(reader_dp)
-        >>> path, line = next(it)
-        >>> path
-        https://raw.githubusercontent.com/pytorch/data/main/LICENSE
-        >>> line
-        b'BSD 3-Clause License'
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper, OnlineReader
+
+        file_url = "https://raw.githubusercontent.com/pytorch/data/main/LICENSE"
+        online_reader_dp = OnlineReader(IterableWrapper([file_url]))
+        reader_dp = online_reader_dp.readlines()
+        it = iter(reader_dp)
+        path, line = next(it)
+        print((path, line))
+
+    Output:
+
+    .. testoutput::
+
+        ('https://raw.githubusercontent.com/pytorch/data/main/LICENSE', b'BSD 3-Clause License')
     """
     source_datapipe: IterDataPipe[str]
 

torchdata/datapipes/iter/load/s3io.py

@@ -40,15 +40,33 @@ class S3FileListerIterDataPipe(IterDataPipe[str]):
         region: region for access files (inferred from credentials by default)
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper, S3FileLister
-        >>> s3_prefixes = IterableWrapper(['s3://bucket-name/folder/', ...])
-        >>> dp_s3_urls = S3FileLister(s3_prefixes)
-        >>> for d in dp_s3_urls:
-        ...     pass
+
+    .. testsetup::
+
+        from unittest import mock
+        from torchdata.datapipes.iter import IterableWrapper, S3FileLister
+
+        file_lister_patch = mock.patch.object(S3FileLister, "__iter__", return_value=iter([]))
+        file_lister_patch.start()
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper, S3FileLister
+
+        s3_prefixes = IterableWrapper(['s3://bucket-name/folder/', ...])
+
+        dp_s3_urls = S3FileLister(s3_prefixes)
+        for d in dp_s3_urls:
+            pass
+
         # Functional API
-        >>> dp_s3_urls = s3_prefixes.list_files_by_s3(request_timeout_ms=100)
-        >>> for d in dp_s3_urls:
-        ...     pass
+        dp_s3_urls = s3_prefixes.list_files_by_s3(request_timeout_ms=100)
+        for d in dp_s3_urls:
+            pass
+
+    .. testcleanup::
+
+        file_lister_patch.stop()
     """
 
     def __init__(
@@ -108,20 +126,38 @@ class S3FileLoaderIterDataPipe(IterDataPipe[Tuple[str, StreamWrapper]]):
         multi_part_download: flag to split each chunk into small packets and download those packets in parallel (enabled by default)
 
     Example:
-        >>> from torchdata.datapipes.iter import IterableWrapper, S3FileLoader
-        >>> dp_s3_urls = IterableWrapper(['s3://bucket-name/folder/', ...]).list_files_by_s3()
+
+    .. testsetup::
+
+        from unittest import mock
+        from torchdata.datapipes.iter import S3FileLister
+
+        file_lister_patch = mock.patch.object(S3FileLister, "__iter__", return_value=iter([]))
+        file_lister_patch.start()
+
+    .. testcode::
+
+        from torchdata.datapipes.iter import IterableWrapper, S3FileLoader
+
+        dp_s3_urls = IterableWrapper(['s3://bucket-name/folder/', ...]).list_files_by_s3()
         # In order to make sure data are shuffled and sharded in the
         # distributed environment, `shuffle`  and `sharding_filter`
         # are required. For detail, please check our tutorial in:
         # https://pytorch.org/data/main/tutorial.html#working-with-dataloader
-        >>> sharded_s3_urls = dp_s3_urls.shuffle().sharding_filter()
-        >>> dp_s3_files = S3FileLoader(sharded_s3_urls)
-        >>> for url, fd in dp_s3_files: # Start loading data
-        ...     data = fd.read()
+        sharded_s3_urls = dp_s3_urls.shuffle().sharding_filter()
+
+        dp_s3_files = S3FileLoader(sharded_s3_urls)
+        for url, fd in dp_s3_files: # Start loading data
+            data = fd.read()
+
         # Functional API
-        >>> dp_s3_files = sharded_s3_urls.load_files_by_s3(buffer_size=256)
-        >>> for url, fd in dp_s3_files:
-        ...     data = fd.read()
+        dp_s3_files = sharded_s3_urls.load_files_by_s3(buffer_size=256)
+        for url, fd in dp_s3_files:
+            data = fd.read()
+
+    .. testcleanup::
+
+        file_lister_patch.stop()
     """
 
     def __init__(