fixups for @shoyer comments

Author: jreback

pandas/core/categorical.py

@@ -18,6 +18,7 @@
                                 is_categorical_dtype, is_integer_dtype, is_object_dtype,
                                 _possibly_infer_to_datetimelike, get_dtype_kinds,
                                 is_list_like, is_sequence, is_null_slice, is_bool,
+                                is_dtypes_equal,
                                 _ensure_platform_int, _ensure_object, _ensure_int64,
                                 _coerce_indexer_dtype, _values_from_object, take_1d)
 from pandas.util.terminal import get_terminal_size
@@ -242,7 +243,7 @@ def __init__(self, values, categories=None, ordered=False, name=None, fastpath=F
             values = values.__array__()
 
         elif isinstance(values, Index):
-            values = np.array(values)
+            #values = np.array(values)
             ordered = True
 
         else:
@@ -311,11 +312,7 @@ def astype(self, dtype):
         """ coerce this type to another dtype """
         if is_categorical_dtype(dtype):
             return self
-        elif is_object_dtype(dtype):
-            return np.array(self)
-
-        raise TypeError('Astype a Categorical to anything other than '
-                        'categorical or object is not supported')
+        return np.array(self, dtype=dtype)
 
     @cache_readonly
     def ndim(self):
@@ -1621,14 +1618,20 @@ def _delegate_method(self, name, *args, **kwargs):
 ##### utility routines #####
 
 def _get_codes_for_values(values, categories):
-    """"
+    """
     utility routine to turn values into codes given the specified categories
     """
 
     from pandas.core.algorithms import _get_data_algo, _hashtables
-    if values.dtype != categories.dtype:
+    if not is_dtypes_equal(values.dtype,categories.dtype):
+        values = _ensure_object(values)
+        categories = _ensure_object(categories)
+
+    if is_object_dtype(values):
         values = _ensure_object(values)
+    if is_object_dtype(categories):
         categories = _ensure_object(categories)
+
     (hash_klass, vec_klass), vals = _get_data_algo(values, _hashtables)
     t = hash_klass(len(categories))
     t.map_locations(_values_from_object(categories))

pandas/core/common.py

@@ -2453,7 +2453,7 @@ def is_dtypes_equal(source, target):
 
     try:
         return source == target
-    except:
+    except TypeError:
 
         # invalid comparison
         # object == category will hit this

pandas/core/index.py

@@ -2365,7 +2365,7 @@ def _evaluate_compare(self, other):
                     return result
                 try:
                     return Index(result)
-                except:  # pragma: no cover
+                except TypeError:
                     return result
 
             return _evaluate_compare

pandas/tests/test_categorical.py

@@ -2696,7 +2696,7 @@ def test_astype_categorical(self):
         tm.assert_categorical_equal(cat,cat.astype('category'))
         tm.assert_almost_equal(np.array(cat),cat.astype('object'))
 
-        self.assertRaises(TypeError, lambda : cat.astype(float))
+        self.assertRaises(ValueError, lambda : cat.astype(float))
 
     def test_to_records(self):