!4649 parameter add example

Merge pull request !4649 from yepei6/comment

mindspore/common/parameter.py

@@ -54,6 +54,33 @@ class Parameter(MetaTensor):
         requires_grad (bool): True if the parameter requires gradient. Default: True.
         layerwise_parallel (bool): A kind of model parallel mode. When layerwise_parallel is true in paralle mode,
             broadcast and gradients communication would not be applied to parameters. Default: False.
+
+    Example:
+        >>> from mindspore import Parameter, Tensor
+        >>> from mindspore.common import initializer as init
+        >>> from mindspore.ops import operations as P
+        >>> from mindspore.nn import Cell
+        >>> import mindspore
+        >>> import numpy as np
+        >>> from mindspore import context
+        >>>
+        >>> class Net(Cell):
+        >>>     def __init__(self):
+        >>>         super(Net, self).__init__()
+        >>>         self.matmul = P.MatMul()
+        >>>         self.weight = Parameter(Tensor(np.ones((1,2))), name="w", requires_grad=True)
+        >>>
+        >>>     def construct(self, x):
+        >>>         out = self.matmul(self.weight, x)
+        >>>     return out
+        >>> context.set_context(mode=context.GRAPH_MODE, device_target="CPU")
+        >>> net = Net()
+        >>> x = Tensor(np.ones((2,1)))
+        >>> net(x)
+        [[2.]]
+        >>> net.weight.set_parameter_data(Tensor(np.zeros((1,2))))
+        >>> net(x)
+        [[0.]]
     """
     __base_type__ = {}