Add note on in-place nature of Normalize, closes #517 (#520)

torchvision/transforms/functional.py

@@ -151,6 +151,9 @@ def to_pil_image(pic, mode=None):
 def normalize(tensor, mean, std):
     """Normalize a tensor image with mean and standard deviation.
 
+    .. note::
+        This transform acts in-place, i.e., it mutates the input tensor.
+
     See :class:`~torchvision.transforms.Normalize` for more details.
 
     Args:

torchvision/transforms/transforms.py

@@ -123,6 +123,9 @@ class Normalize(object):
     will normalize each channel of the input ``torch.*Tensor`` i.e.
     ``input[channel] = (input[channel] - mean[channel]) / std[channel]``
 
+    .. note::
+        This transform acts in-place, i.e., it mutates the input tensor.
+
     Args:
         mean (sequence): Sequence of means for each channel.
         std (sequence): Sequence of standard deviations for each channel.