add Compose doc

hapi/datasets/flowers.py

@@ -121,7 +121,7 @@ class Flowers(Dataset):
         image = np.array(Image.open(io.BytesIO(image)))
 
         if self.transform is not None:
-            image, label = self.transform(image, label)
+            image = self.transform(image)
 
         return image, label
 

hapi/datasets/mnist.py

@@ -149,7 +149,7 @@ class MNIST(Dataset):
     def __getitem__(self, idx):
         image, label = self.images[idx], self.labels[idx]
         if self.transform is not None:
-            image, label = self.transform(image, label)
+            image = self.transform(image)
         return image, label
 
     def __len__(self):

hapi/vision/transforms/transforms.py

@@ -61,6 +61,24 @@ class Compose(object):
     Args:
         transforms (list of ``Transform`` objects): list of transforms to compose.
 
+    Returns:
+        A compose object which is callable, __call__ for this Compose
+        object will call each given :attr:`transforms` sequencely.
+
+    Examples:
+    
+        .. code-block:: python
+
+            from hapi.datasets import Flowers
+            from hapi.vision.transforms import Compose, ColorJitter, Resize
+
+            transform = Compose([ColorJitter(), Resize(size=608)])
+            flowers = Flowers(mode='test', transform=transform)
+
+            for i in range(10):
+                sample = flowers[i]
+                print(sample[0].shape, sample[1])
+
     """
 
     def __init__(self, transforms):