added is_valid_file parameter to datasets folders (#867)

* added is_valid_file option

* small fixes

* fixes

* flake8 fixes

* some test

* flake8 fixes

* improvements

* modifications on tests
* fixes

* minor fix

test/test_folder.py

@@ -36,6 +36,20 @@ class Tester(unittest.TestCase):
         outputs = sorted([dataset[i] for i in range(len(dataset))])
         self.assertEqual(imgs, outputs)
 
+        dataset = ImageFolder(Tester.root, loader=lambda x: x, is_valid_file=lambda x: '3' in x)
+        self.assertEqual(sorted(Tester.classes), sorted(dataset.classes))
+        for cls in Tester.classes:
+            self.assertEqual(cls, dataset.classes[dataset.class_to_idx[cls]])
+        class_a_idx = dataset.class_to_idx['a']
+        class_b_idx = dataset.class_to_idx['b']
+        imgs_a = [(img_path, class_a_idx)for img_path in Tester.class_a_images if '3' in img_path]
+        imgs_b = [(img_path, class_b_idx)for img_path in Tester.class_b_images if '3' in img_path]
+        imgs = sorted(imgs_a + imgs_b)
+        self.assertEqual(imgs, dataset.imgs)
+
+        outputs = sorted([dataset[i] for i in range(len(dataset))])
+        self.assertEqual(imgs, outputs)
+
     def test_transform(self):
         return_value = get_file_path_2('test/assets/dataset/a/a1.png')
 

torchvision/datasets/folder.py

@@ -32,18 +32,24 @@ def is_image_file(filename):
     return has_file_allowed_extension(filename, IMG_EXTENSIONS)
 
 
-def make_dataset(dir, class_to_idx, extensions):
+def make_dataset(dir, class_to_idx, extensions=None, is_valid_file=None):
     images = []
     dir = os.path.expanduser(dir)
+    if extensions is None and is_valid_file is None:
+        raise ValueError("Both extensions and is_valid_file cannot be None")
+    if extensions is not None and is_valid_file is not None:
+        raise ValueError("One of the extensions and is_valid_file should be None")
+    if extensions is not None:
+        def is_valid_file(x):
+            return has_file_allowed_extension(x, extensions)
     for target in sorted(class_to_idx.keys()):
         d = os.path.join(dir, target)
         if not os.path.isdir(d):
             continue
-
         for root, _, fnames in sorted(os.walk(d)):
             for fname in sorted(fnames):
-                if has_file_allowed_extension(fname, extensions):
                 path = os.path.join(root, fname)
+                if is_valid_file(path):
                     item = (path, class_to_idx[target])
                     images.append(item)
 
@@ -65,11 +71,15 @@ class DatasetFolder(VisionDataset):
         root (string): Root directory path.
         loader (callable): A function to load a sample given its path.
         extensions (tuple[string]): A list of allowed extensions.
+            both extensions and is_valid_file should not be passed.
         transform (callable, optional): A function/transform that takes in
             a sample and returns a transformed version.
             E.g, ``transforms.RandomCrop`` for images.
         target_transform (callable, optional): A function/transform that takes
             in the target and transforms it.
+        is_valid_file (callable, optional): A function that takes path of an Image file
+            and check if the file is a valid_file (used to check of corrupt files)
+            both extensions and is_valid_file should not be passed.
 
      Attributes:
         classes (list): List of the class names.
@@ -78,12 +88,12 @@ class DatasetFolder(VisionDataset):
         targets (list): The class_index value for each image in the dataset
     """
 
-    def __init__(self, root, loader, extensions, transform=None, target_transform=None):
+    def __init__(self, root, loader, extensions=None, transform=None, target_transform=None, is_valid_file=None):
         super(DatasetFolder, self).__init__(root)
         self.transform = transform
         self.target_transform = target_transform
         classes, class_to_idx = self._find_classes(self.root)
-        samples = make_dataset(self.root, class_to_idx, extensions)
+        samples = make_dataset(self.root, class_to_idx, extensions, is_valid_file)
         if len(samples) == 0:
             raise (RuntimeError("Found 0 files in subfolders of: " + self.root + "\n"
                                 "Supported extensions are: " + ",".join(extensions)))
@@ -184,6 +194,8 @@ class ImageFolder(DatasetFolder):
         target_transform (callable, optional): A function/transform that takes in the
             target and transforms it.
         loader (callable, optional): A function to load an image given its path.
+        is_valid_file (callable, optional): A function that takes path of an Image file
+            and check if the file is a valid_file (used to check of corrupt files)
 
      Attributes:
         classes (list): List of the class names.
@@ -192,8 +204,9 @@ class ImageFolder(DatasetFolder):
     """
 
     def __init__(self, root, transform=None, target_transform=None,
-                 loader=default_loader):
-        super(ImageFolder, self).__init__(root, loader, IMG_EXTENSIONS,
+                 loader=default_loader, is_valid_file=None):
+        super(ImageFolder, self).__init__(root, loader, IMG_EXTENSIONS if is_valid_file is None else None,
                                           transform=transform,
-                                          target_transform=target_transform)
+                                          target_transform=target_transform,
+                                          is_valid_file=is_valid_file)
         self.imgs = self.samples