!1853 Fix initializer

Merge pull request !1853 from amongo/FixInitializer

mindspore/common/initializer.py

@@ -338,12 +338,6 @@ def initializer(init, shape=None, dtype=mstype.float32):
                              "the variable shape {}.".format(list(init.shape()), shape))
         return init
 
-    if isinstance(init, str):
-        init_obj = _INITIALIZER_ALIAS[init.lower()]()
-        if init_obj is None:
-            raise ValueError("The class corresponding to '{}' was not found.".format(init))
-        init = init_obj
-
     if isinstance(shape, list):
         shape = tuple(shape)
     elif isinstance(shape, numbers.Number):
@@ -354,6 +348,15 @@ def initializer(init, shape=None, dtype=mstype.float32):
         raise ValueError("Error shape={}".format(shape))
 
     if isinstance(init, Initializer):
+        init.shape = init.shape if init.shape is not None else shape
+        init.dtype = init.dtype if init.dtype is not None else dtype
+        return init
+
+    if isinstance(init, str):
+        init_obj = _INITIALIZER_ALIAS[init.lower()]()
+        if init_obj is None:
+            raise ValueError("The class corresponding to '{}' was not found.".format(init))
+        init = init_obj
         init.shape = shape
         init.dtype = dtype
         return init

tests/ut/python/utils/test_initializer.py

@@ -141,7 +141,18 @@ def test_init_abnormal():
     with py.raises(TypeError):
         init.initializer([''], [5, 4], ms.float32)
 
-
+def test_initializer_reinit():
+    weights = init.initializer("XavierUniform", shape=(10, 1, 10, 10), dtype=ms.float16)
+    assert weights.dtype == ms.float16
+    assert weights.shape == (10, 1, 10, 10)
+    weights = init.initializer(weights)
+    assert weights.dtype == ms.float16
+    assert weights.shape == (10, 1, 10, 10)
+    weights.shape = None
+    weights = init.initializer(weights, (10, 1))
+    assert weights.dtype == ms.float16
+    assert weights.shape == (10, 1)
+    
 def test_init_xavier_uniform():
     """ test_init_xavier_uniform """
     gain = 1.2