feat(mge): remove F.identity

GitOrigin-RevId: 858be627acf028a46c57bde55161a85ff47d157f

imperative/python/megengine/functional/tensor.py

@@ -42,7 +42,6 @@ __all__ = [
     "full",
     "full_like",
     "gather",
-    "identity",
     "linspace",
     "ones",
     "ones_like",
@@ -178,18 +177,6 @@ def full_like(inp: Tensor, value: Union[int, float]) -> Tensor:
     return full(inp.shape, value, dtype=inp.dtype, device=inp.device)
 
 
-def identity(inp: Tensor) -> Tensor:
-    """Applies an identity transformation to input tensor.
-
-    :param inp: input tensor.
-    :return: output tensor.
-    """
-    op = builtin.Identity()
-    (data,) = convert_inputs(inp)
-    (output,) = apply(op, data)
-    return output
-
-
 def broadcast_to(inp: Tensor, shape: Union[int, Iterable[int]]) -> Tensor:
     """
     Broadcasts a tensor to given shape.

imperative/python/megengine/functional/utils.py

@@ -11,7 +11,8 @@ from typing import Iterable, Union
 
 import numpy as np
 
-from ..core.ops.builtin import Copy
+from ..core._wrap import device as as_device
+from ..core.ops.builtin import Copy, Identity
 from ..core.tensor import Tensor
 from ..core.tensor.core import apply
 from .math import topk as _topk
@@ -63,12 +64,12 @@ def accuracy(
     return accs
 
 
-def copy(inp, cn):
+def copy(inp, device=None):
     r"""
     Copies tensor to another device.
 
     :param inp: input tensor.
-    :param cn: destination device.
+    :param device: destination device.
 
     Examples:
 
@@ -88,4 +89,6 @@ def copy(inp, cn):
 
         [1 2 3]
     """
-    return apply(Copy(comp_node=cn), inp)[0]
+    if device is None:
+        return apply(Identity(), inp)[0]
+    return apply(Copy(comp_node=as_device(device).to_c()), inp)[0]

imperative/python/megengine/module/identity.py

@@ -6,7 +6,7 @@
 # Unless required by applicable law or agreed to in writing,
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-from ..functional import identity
+from ..functional import copy
 from .module import Module
 
 
@@ -14,4 +14,4 @@ class Identity(Module):
     r"""A placeholder identity operator that will ignore any argument."""
 
     def forward(self, x):
-        return identity(x)
+        return copy(x)

imperative/python/test/unit/functional/test_tensor.py

@@ -314,7 +314,7 @@ def test_device():
 
 def test_identity():
     x = tensor(np.random.random((5, 10)).astype(np.float32))
-    y = F.identity(x)
+    y = F.copy(x)
     np.testing.assert_equal(y.numpy(), x)