Unify Index._dir_* with Series implementation

pandas/core/base.py

@@ -72,7 +72,35 @@ def __repr__(self):
         return str(self)
 
 
-class PandasObject(StringMixin):
+class DirNamesMixin(object):
+    _accessors = frozenset([])
+
+    def _dir_deletions(self):
+        """ delete unwanted __dir__ for this object """
+        return self._accessors
+
+    def _dir_additions(self):
+        """ add addtional __dir__ for this object """
+        rv = set()
+        for accessor in self._accessors:
+            try:
+                getattr(self, accessor)
+                rv.add(accessor)
+            except AttributeError:
+                pass
+        return rv
+
+    def __dir__(self):
+        """
+        Provide method name lookup and completion
+        Only provide 'public' methods
+        """
+        rv = set(dir(type(self)))
+        rv = (rv - self._dir_deletions()) | self._dir_additions()
+        return sorted(rv)
+
+
+class PandasObject(StringMixin, DirNamesMixin):
 
     """baseclass for various pandas objects"""
 
@@ -91,23 +119,6 @@ def __unicode__(self):
         # Should be overwritten by base classes
         return object.__repr__(self)
 
-    def _dir_additions(self):
-        """ add addtional __dir__ for this object """
-        return set()
-
-    def _dir_deletions(self):
-        """ delete unwanted __dir__ for this object """
-        return set()
-
-    def __dir__(self):
-        """
-        Provide method name lookup and completion
-        Only provide 'public' methods
-        """
-        rv = set(dir(type(self)))
-        rv = (rv - self._dir_deletions()) | self._dir_additions()
-        return sorted(rv)
-
     def _reset_cache(self, key=None):
         """
         Reset cached properties. If ``key`` is passed, only clears that key.
@@ -140,7 +151,7 @@ class NoNewAttributesMixin(object):
 
     Prevents additional attributes via xxx.attribute = "something" after a
     call to `self.__freeze()`. Mainly used to prevent the user from using
-    wrong attrirbutes on a accessor (`Series.cat/.str/.dt`).
+    wrong attributes on a accessor (`Series.cat/.str/.dt`).
 
     If you really want to add a new attribute at a later time, you need to use
     `object.__setattr__(self, key, value)`.

pandas/core/generic.py

@@ -192,8 +192,9 @@ def __unicode__(self):
 
     def _dir_additions(self):
         """ add the string-like attributes from the info_axis """
-        return set([c for c in self._info_axis
-                    if isinstance(c, string_types) and isidentifier(c)])
+        additions = set([c for c in self._info_axis
+                         if isinstance(c, string_types) and isidentifier(c)])
+        return PandasObject._dir_additions(self).union(additions)
 
     @property
     def _constructor_sliced(self):

pandas/core/indexes/base.py

@@ -52,7 +52,7 @@
 import pandas.core.sorting as sorting
 from pandas.io.formats.printing import pprint_thing
 from pandas.core.ops import _comp_method_OBJECT_ARRAY
-from pandas.core.strings import StringAccessorMixin
+from pandas.core import strings
 from pandas.core.config import get_option
 
 
@@ -98,7 +98,7 @@ def _new_Index(cls, d):
     return cls.__new__(cls, **d)
 
 
-class Index(IndexOpsMixin, StringAccessorMixin, PandasObject):
+class Index(IndexOpsMixin, PandasObject):
     """
     Immutable ndarray implementing an ordered, sliceable set. The basic object
     storing axis labels for all pandas objects
@@ -151,6 +151,12 @@ class Index(IndexOpsMixin, StringAccessorMixin, PandasObject):
 
     _engine_type = libindex.ObjectEngine
 
+    _accessors = frozenset(['dt', 'str', 'cat'])
+
+    # String Methods
+    str = base.AccessorProperty(strings.StringMethods,
+                                strings.StringMethods._make_accessor)
+
     def __new__(cls, data=None, dtype=None, copy=False, name=None,
                 fastpath=False, tupleize_cols=True, **kwargs):
 

pandas/core/indexes/datetimelike.py

@@ -125,6 +125,15 @@ def ceil(self, freq):
 class DatetimeIndexOpsMixin(object):
     """ common ops mixin to support a unified inteface datetimelike Index """
 
+    @property
+    def dt(self):
+        """
+        For a datetime-like Index object, `self.dt` returns `self` so that
+        datetime-like attributes can be accessed symmetrically for Index
+        and Series objects.
+        """
+        return self
+
     def equals(self, other):
         """
         Determines if two Index objects contain the same elements.

pandas/core/series.py

@@ -114,8 +114,7 @@ def wrapper(self):
 # Series class
 
 
-class Series(base.IndexOpsMixin, strings.StringAccessorMixin,
-             generic.NDFrame,):
+class Series(base.IndexOpsMixin, generic.NDFrame):
     """
     One-dimensional ndarray with axis labels (including time series).
 
@@ -2934,18 +2933,9 @@ def _make_cat_accessor(self):
 
     cat = base.AccessorProperty(CategoricalAccessor, _make_cat_accessor)
 
-    def _dir_deletions(self):
-        return self._accessors
-
-    def _dir_additions(self):
-        rv = set()
-        for accessor in self._accessors:
-            try:
-                getattr(self, accessor)
-                rv.add(accessor)
-            except AttributeError:
-                pass
-        return rv
+    # String Methods
+    str = base.AccessorProperty(strings.StringMethods,
+                                strings.StringMethods._make_accessor)
 
 
 Series._setup_axes(['index'], info_axis=0, stat_axis=0, aliases={'rows': 0})

pandas/core/strings.py

@@ -16,7 +16,7 @@
 
 from pandas.core.algorithms import take_1d
 import pandas.compat as compat
-from pandas.core.base import AccessorProperty, NoNewAttributesMixin
+from pandas.core.base import NoNewAttributesMixin
 from pandas.util._decorators import Appender
 import re
 import pandas._libs.lib as lib
@@ -1890,18 +1890,15 @@ def rindex(self, sub, start=0, end=None):
                                docstring=_shared_docs['ismethods'] %
                                _shared_docs['isdecimal'])
 
-
-class StringAccessorMixin(object):
-    """ Mixin to add a `.str` acessor to the class."""
-
     # string methods
-    def _make_str_accessor(self):
+    @classmethod
+    def _make_accessor(cls, data):
         from pandas.core.index import Index
 
-        if (isinstance(self, ABCSeries) and
-                not ((is_categorical_dtype(self.dtype) and
-                      is_object_dtype(self.values.categories)) or
-                     (is_object_dtype(self.dtype)))):
+        if (isinstance(data, ABCSeries) and
+                not ((is_categorical_dtype(data.dtype) and
+                      is_object_dtype(data.values.categories)) or
+                     (is_object_dtype(data.dtype)))):
             # it's neither a string series not a categorical series with
             # strings inside the categories.
             # this really should exclude all series with any non-string values
@@ -1910,30 +1907,18 @@ def _make_str_accessor(self):
             raise AttributeError("Can only use .str accessor with string "
                                  "values, which use np.object_ dtype in "
                                  "pandas")
-        elif isinstance(self, Index):
+        elif isinstance(data, Index):
             # can't use ABCIndex to exclude non-str
 
             # see scc/inferrence.pyx which can contain string values
             allowed_types = ('string', 'unicode', 'mixed', 'mixed-integer')
-            if self.inferred_type not in allowed_types:
+            if data.inferred_type not in allowed_types:
                 message = ("Can only use .str accessor with string values "
                            "(i.e. inferred_type is 'string', 'unicode' or "
                            "'mixed')")
                 raise AttributeError(message)
-            if self.nlevels > 1:
+            if data.nlevels > 1:
                 message = ("Can only use .str accessor with Index, not "
                            "MultiIndex")
                 raise AttributeError(message)
-        return StringMethods(self)
-
-    str = AccessorProperty(StringMethods, _make_str_accessor)
-
-    def _dir_additions(self):
-        return set()
-
-    def _dir_deletions(self):
-        try:
-            getattr(self, 'str')
-        except AttributeError:
-            return set(['str'])
-        return set()
+        return cls(data)