BUG: Added 'O' to valid dtype list for pandas_dtype

Author: analyticalmonk

pandas/core/dtypes/common.py

@@ -748,7 +748,7 @@ def pandas_dtype(dtype):
     # also catch some valid dtypes such as object, np.object_ and 'object'
     # which we safeguard against by catching them earlier and returning
     # np.dtype(valid_dtype) before this condition is evaluated.
-    if dtype in [object, np.object_, 'object']:
+    if dtype in [object, np.object_, 'object', 'O']:
         return npdtype
     elif npdtype.kind == 'O':
         raise TypeError('dtype {0} not understood'.format(dtype))

pandas/tests/dtypes/test_common.py

@@ -23,7 +23,7 @@ def test_invalid_dtype_error(self):
             with tm.assertRaisesRegexp(TypeError, msg):
                 pandas_dtype(dtype)
 
-        valid_list = [object, 'float64', np.object_, np.dtype('object'),
+        valid_list = [object, 'float64', np.object_, np.dtype('object'), 'O',
                       np.float64, float, np.dtype('float64')]
         for dtype in valid_list:
             pandas_dtype(dtype)