Implement reshape_as

aten/src/ATen/native/TensorShape.cpp

@@ -265,6 +265,10 @@ Tensor reshape(const Tensor& self, IntList proposed_shape) {
   return at::_unsafe_view(self.clone(), shape);
 }
 
+Tensor reshape_as(const Tensor& self, const Tensor& other) {
+  return self.reshape(other.sizes());
+}
+
 Tensor select(const Tensor& self, int64_t dim, int64_t index) {
   int64_t ndim = self.dim();
   AT_CHECK(ndim > 0, "select() cannot be applied to a 0-dim tensor.");

aten/src/ATen/native/native_functions.yaml

@@ -1096,6 +1096,9 @@
 
 - func: reshape(Tensor self, IntList shape) -> Tensor
 
+- func: reshape_as(Tensor self, Tensor other) -> Tensor
+  variants: method
+
 - func: RoiPooling2d_forward(Tensor input, Tensor rois, int64_t pooledHeight, int64_t pooledWidth, double spatialScale) -> (Tensor, Tensor)
   variants: function
   dispatch:

docs/source/tensors.rst

@@ -329,6 +329,7 @@ view of a storage and defines numeric operations on it.
    .. automethod:: repeat
    .. automethod:: requires_grad_
    .. automethod:: reshape
+   .. automethod:: reshape_as
    .. automethod:: resize_
    .. automethod:: resize_as_
    .. automethod:: round

test/test_autograd.py

@@ -2620,6 +2620,9 @@ class dont_convert(tuple):
     ('reshape', (S,), (S,), '1d'),
     ('reshape', (), (dont_convert(()),), 'scalar_to_scalar'),
     ('reshape', (), (1,), 'scalar_to_1d'),
+    ('reshape_as', (S, S, S), (non_differentiable(torch.rand(S * S, S)),)),
+    ('reshape_as', (), (non_differentiable(torch.tensor(42.)),), 'scalar'),
+    ('reshape_as', (), (non_differentiable(torch.rand(1, 1)),), 'scalar_to_dims'),
     ('flip', (S, S, S), ([0],), 'd0'),
     ('flip', (S, S, S), ([0, 1, 2],), 'd012'),
     ('flip', (S, S, S), ([0, 2],), 'd02'),

test/test_torch.py

@@ -6027,6 +6027,11 @@ def test_reshape(self):
             self.assertEqual(empty.reshape([1, -1]).shape, (0,))
         self.assertRaises(RuntimeError, lambda: empty.reshape(1))
 
+        x = torch.randn(3, 3)
+        self.assertEqual(x.data_ptr(), x.reshape_as(torch.rand(9)).data_ptr())
+        self.assertEqual(x.data_ptr(), x.reshape_as(torch.rand(1, 9, 1)).data_ptr())
+        self.assertRaises(RuntimeError, lambda: x.reshape_as(torch.rand(10)))
+
     @skipIfNoZeroSize
     def test_empty_reshape(self):
         x = torch.randn(0, 6)

tools/autograd/derivatives.yaml

@@ -579,7 +579,7 @@
   self: repeat_backward(grad, self.dim(), repeats)
 
 # DO NOT define a backward for reshape!
-# reshape is special in that it sometimes returns a view, and somtimes not.
+# reshape is special in that it sometimes returns a view, and sometimes not.
 # Defining a backward will make codegen spit out the forward call as
 #     as_variable(baseType->reshape(self)),
 # making it impossible (hard) to detect when it is actually a view.

torch/_tensor_docs.py

@@ -1666,6 +1666,20 @@ def callable(a, b) -> number
 See :func:`torch.reshape`
 """)
 
+add_docstr_all('reshape_as',
+               r"""
+reshape_as(other) -> Tensor
+
+Returns this tensor as the same shape as :attr:`other`.
+``self.reshape_as(other)`` is equivalent to ``self.reshape(other.sizes())``.
+
+Please see :meth:`~Tensor.reshape` for more information about ``reshape``.
+
+Args:
+    other (:class:`torch.Tensor`): The result tensor has the same shape
+        as :attr:`other`.
+""")
+
 add_docstr_all('resize_',
                r"""
 resize_(*sizes) -> Tensor
@@ -2407,6 +2421,20 @@ def callable(a, b) -> number
 
 """)
 
+add_docstr_all('view_as',
+               r"""
+view_as(other) -> Tensor
+
+View this tensor as the same size as :attr:`other`.
+``self.view_as(other)`` is equivalent to ``self.view(other.size())``.
+
+Please see :meth:`~Tensor.view` for more information about ``view``.
+
+Args:
+    other (:class:`torch.Tensor`): The result tensor has the same size
+        as :attr:`other`.
+""")
+
 add_docstr_all('expand',
                r"""
 expand(*sizes) -> Tensor
@@ -2445,6 +2473,20 @@ def callable(a, b) -> number
             [ 3,  3,  3,  3]])
 """)
 
+add_docstr_all('expand_as',
+               r"""
+expand_as(other) -> Tensor
+
+Expand this tensor to the same size as :attr:`other`.
+``self.expand_as(other)`` is equivalent to ``self.expand(other.size())``.
+
+Please see :meth:`~Tensor.expand` for more information about ``expand``.
+
+Args:
+    other (:class:`torch.Tensor`): The result tensor has the same size
+        as :attr:`other`.
+""")
+
 add_docstr_all('zero_',
                r"""
 zero_() -> Tensor

torch/tensor.py

@@ -219,18 +219,6 @@ def share_memory_(self):
         self.storage().share_memory_()
         return self
 
-    def view_as(self, tensor):
-        r"""view_as(other) -> Tensor
-
-        View this tensor as the same size as :attr:`other`.
-        ``self.view_as(other)`` is equivalent to ``self.view(other.size())``.
-
-        Args:
-            other (:class:`torch.Tensor`): The result tensor has the same size
-                as :attr:`other.size()`.
-        """
-        return self.view(tensor.size())
-
     def __reversed__(self):
         r"""Reverses the tensor along dimension 0."""
         if self.dim() == 0: