CelebA: track attr names, support split="all", code cleanup (#1008)

* CelebA: track attr names, support split="all", code cleanup

* fix typo

torchvision/datasets/celeba.py

+from functools import partial
 import torch
 import os
 import PIL
@@ -10,7 +11,7 @@ class CelebA(VisionDataset):
 
     Args:
         root (string): Root directory where images are downloaded to.
-        split (string): One of {'train', 'valid', 'test'}.
+        split (string): One of {'train', 'valid', 'test', 'all'}.
             Accordingly dataset is selected.
         target_type (string or list, optional): Type of target to use, ``attr``, ``identity``, ``bbox``,
             or ``landmarks``. Can also be a list to output a tuple with all specified target types.
@@ -78,32 +79,28 @@ class CelebA(VisionDataset):
             split = 1
         elif split.lower() == "test":
             split = 2
+        elif split.lower() == "all":
+            split = None
         else:
-            raise ValueError('Wrong split entered! Please use split="train" '
-                             'or split="valid" or split="test"')
+            raise ValueError('Wrong split entered! Please use "train", '
+                             '"valid", "test", or "all"')
 
-        with open(os.path.join(self.root, self.base_folder, "list_eval_partition.txt"), "r") as f:
-            splits = pandas.read_csv(f, delim_whitespace=True, header=None, index_col=0)
+        fn = partial(os.path.join, self.root, self.base_folder)
+        splits = pandas.read_csv(fn("list_eval_partition.txt"), delim_whitespace=True, header=None, index_col=0)
+        identity = pandas.read_csv(fn("identity_CelebA.txt"), delim_whitespace=True, header=None, index_col=0)
+        bbox = pandas.read_csv(fn("list_bbox_celeba.txt"), delim_whitespace=True, header=1, index_col=0)
+        landmarks_align = pandas.read_csv(fn("list_landmarks_align_celeba.txt"), delim_whitespace=True, header=1)
+        attr = pandas.read_csv(fn("list_attr_celeba.txt"), delim_whitespace=True, header=1)
 
-        with open(os.path.join(self.root, self.base_folder, "identity_CelebA.txt"), "r") as f:
-            self.identity = pandas.read_csv(f, delim_whitespace=True, header=None, index_col=0)
+        mask = slice(None) if split is None else (splits[1] == split)
 
-        with open(os.path.join(self.root, self.base_folder, "list_bbox_celeba.txt"), "r") as f:
-            self.bbox = pandas.read_csv(f, delim_whitespace=True, header=1, index_col=0)
-
-        with open(os.path.join(self.root, self.base_folder, "list_landmarks_align_celeba.txt"), "r") as f:
-            self.landmarks_align = pandas.read_csv(f, delim_whitespace=True, header=1)
-
-        with open(os.path.join(self.root, self.base_folder, "list_attr_celeba.txt"), "r") as f:
-            self.attr = pandas.read_csv(f, delim_whitespace=True, header=1)
-
-        mask = (splits[1] == split)
         self.filename = splits[mask].index.values
-        self.identity = torch.as_tensor(self.identity[mask].values)
-        self.bbox = torch.as_tensor(self.bbox[mask].values)
-        self.landmarks_align = torch.as_tensor(self.landmarks_align[mask].values)
-        self.attr = torch.as_tensor(self.attr[mask].values)
+        self.identity = torch.as_tensor(identity[mask].values)
+        self.bbox = torch.as_tensor(bbox[mask].values)
+        self.landmarks_align = torch.as_tensor(landmarks_align[mask].values)
+        self.attr = torch.as_tensor(attr[mask].values)
         self.attr = (self.attr + 1) // 2  # map from {-1, 1} to {0, 1}
+        self.attr_names = list(attr.columns)
 
     def _check_integrity(self):
         for (_, md5, filename) in self.file_list: