add AvgPooling layer

mindspore/nn/layer/pooling.py

@@ -18,6 +18,7 @@ from mindspore.ops import functional as F
 from mindspore._checkparam import Validator as validator
 from ... import context
 from ..cell import Cell
+from ..._checkparam import Rel
 
 
 class _PoolNd(Cell):
@@ -263,10 +264,15 @@ class AvgPool1d(_PoolNd):
                  stride=1,
                  pad_mode="valid"):
         super(AvgPool1d, self).__init__(kernel_size, stride, pad_mode)
+        validator.check_type('kernel_size', kernel_size, [int,])
+        validator.check_type('stride', stride, [int,])
+        self.padding = validator.check_string('pad_mode', pad_mode.upper(), ['VALID', 'SAME'])
         if not isinstance(kernel_size, int):
+            validator.check_integer("kernel_size", kernel_size, 1, Rel.GE)
             raise ValueError("kernel_size should be 1 int number but got {}".
                              format(kernel_size))
         if not isinstance(stride, int):
+            validator.check_integer("stride", stride, 1, Rel.GE)
             raise ValueError("stride should be 1 int number but got {}".format(stride))
         self.kernel_size = (1, kernel_size)
         self.stride = (1, stride)