Add new api: is_tensor (#28111)

* Add new api: is_tensor

* Add new api: is_tensor

* Add new api: is_tensor

* Add new api: is_tensor

python/paddle/__init__.py

@@ -108,6 +108,7 @@ from .tensor.logic import not_equal  #DEFINE_ALIAS
 from .tensor.logic import allclose  #DEFINE_ALIAS
 from .tensor.logic import equal_all  #DEFINE_ALIAS
 # from .tensor.logic import isnan        #DEFINE_ALIAS
+from .tensor.logic import is_tensor  #DEFINE_ALIAS
 from .tensor.manipulation import cast  #DEFINE_ALIAS
 from .tensor.manipulation import concat  #DEFINE_ALIAS
 from .tensor.manipulation import expand  #DEFINE_ALIAS

python/paddle/fluid/tests/unittests/test_is_tensor.py

@@ -0,0 +1,56 @@
+#   Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import unittest
+import paddle
+
+DELTA = 0.00001
+
+
+class TestIsTensorApi(unittest.TestCase):
+    def test_is_tensor_real(self, dtype="float32"):
+        """Test is_tensor api with a real tensor
+        """
+        paddle.disable_static()
+        x = paddle.rand([3, 2, 4], dtype=dtype)
+        self.assertTrue(paddle.is_tensor(x))
+
+    def test_is_tensor_complex(self, dtype="float32"):
+        """Test is_tensor api with a complex tensor
+        """
+        paddle.disable_static()
+        r = paddle.to_tensor(1)
+        i = paddle.to_tensor(2)
+        x = paddle.ComplexTensor(r, i)
+        self.assertTrue(paddle.is_tensor(x))
+
+    def test_is_tensor_list(self, dtype="float32"):
+        """Test is_tensor api with a list
+        """
+        paddle.disable_static()
+        x = [1, 2, 3]
+        self.assertFalse(paddle.is_tensor(x))
+
+    def test_is_tensor_number(self, dtype="float32"):
+        """Test is_tensor api with a number
+        """
+        paddle.disable_static()
+        x = 5
+        self.assertFalse(paddle.is_tensor(x))
+
+
+if __name__ == '__main__':
+    unittest.main()

python/paddle/tensor/__init__.py

@@ -71,6 +71,7 @@ from .logic import not_equal  #DEFINE_ALIAS
 from .logic import allclose  #DEFINE_ALIAS
 from .logic import equal_all  #DEFINE_ALIAS
 # from .logic import isnan        #DEFINE_ALIAS
+from .logic import is_tensor  #DEFINE_ALIAS
 from .manipulation import cast  #DEFINE_ALIAS
 from .manipulation import concat  #DEFINE_ALIAS
 from .manipulation import expand  #DEFINE_ALIAS

python/paddle/tensor/logic.py

@@ -19,6 +19,8 @@ from ..fluid.layers.layer_function_generator import templatedoc
 from .. import fluid
 from ..fluid.framework import in_dygraph_mode
 from paddle.common_ops_import import *
+from ..framework import VarBase as Tensor
+from ..framework import ComplexVariable as ComplexTensor
 
 # TODO: define logic functions of a tensor  
 from ..fluid.layers import is_empty  #DEFINE_ALIAS
@@ -43,6 +45,7 @@ __all__ = [
     'logical_xor',
     'not_equal',
     'allclose',
+    'is_tensor'
     #       'isnan'
 ]
 
@@ -372,3 +375,35 @@ def not_equal(x, y, name=None):
     """
     out = fluid.layers.not_equal(x, y, name=name, cond=None)
     return out
+
+
+def is_tensor(x):
+    """
+
+    This function tests whether input object is a paddle.Tensor or a paddle.ComplexTensor.
+
+    Args:
+        x (object): Object to test.
+
+    Returns:
+        A boolean value. True if 'x' is a paddle.Tensor or a paddle.ComplexTensor, otherwise False.
+
+    Examples:
+        .. code-block:: python
+
+            import paddle
+
+            input1 = paddle.rand(shape=[2, 3, 5], dtype='float32')
+            check = paddle.is_tensor(input1)
+            print(check)  #True
+
+            input2 = paddle.ComplexTensor(input1, input1)
+            check = paddle.is_tensor(input2)
+            print(check)  #True
+
+            input3 = [1, 4]
+            check = paddle.is_tensor(input3)
+            print(check)  #False
+            
+    """
+    return isinstance(x, Tensor) or isinstance(x, ComplexTensor)