remove PeriodIndex workaround

Author: chris-b1

doc/source/whatsnew/v0.19.0.txt

@@ -948,7 +948,7 @@ Bug Fixes
 - Bug in ``pd.read_hdf()`` returns incorrect result when a ``DataFrame`` with a ``categorical`` column and a query which doesn't match any values (:issue:`13792`)
 - Bug in ``pd.to_datetime()`` raise ``AttributeError`` with NaN and the other string is not valid when errors='ignore' (:issue:`12424`)
 
-- Bug in ``groupby`` where a ``TimeGrouper`` selection is used with the ``key`` or ``level`` arguments with a ``PeriodIndex`` (:issue:`14008`)
+
 - Bug in ``Series`` comparison operators when dealing with zero dim NumPy arrays (:issue:`13006`)
 - Bug in ``groupby`` where ``apply`` returns different result depending on whether first result is ``None`` or not (:issue:`12824`)
 - Bug in ``groupby(..).nth()`` where the group key is included inconsistently if called after ``.head()/.tail()`` (:issue:`12839`)

pandas/core/groupby.py

@@ -257,8 +257,6 @@ def _set_grouper(self, obj, sort=False, converter=None):
         obj : the subject object
         sort : bool, default False
             whether the resulting grouper should be sorted
-        converter : callable, optional
-            conversion to apply the grouper after selection
         """
 
         if self.key is not None and self.level is not None:
@@ -298,8 +296,6 @@ def _set_grouper(self, obj, sort=False, converter=None):
                            convert=False, is_copy=False)
 
         self.obj = obj
-        if converter is not None:
-            ax = converter(ax)
         self.grouper = ax
         return self.grouper
 

pandas/tseries/resample.py

@@ -88,11 +88,13 @@ def __init__(self, obj, groupby=None, axis=0, kind=None, **kwargs):
         self.from_selection = False
 
         if self.groupby is not None:
-            # bookeeping to disallow upsampling if not resampling on index
+            # upsampling and PeriodIndex resampling do not work
+            # if resampling on a column or mi level
+            # this is state used to catch and raise an error
             self.from_selection = (self.groupby.key is not None or
                                    self.groupby.level is not None)
-            obj, converter = self._convert_obj(obj)
-            self.groupby._set_grouper(obj, sort=True, converter=converter)
+            obj = self._convert_obj(obj)
+            self.groupby._set_grouper(obj, sort=True)
 
     def __unicode__(self):
         """ provide a nice str repr of our rolling object """
@@ -208,7 +210,6 @@ def __setitem__(self, attr, value):
     def _convert_obj(self, obj):
         """
         provide any conversions for the object in order to correctly handle
-        and returns a converter function to be applied to grouping selection
 
         Parameters
         ----------
@@ -217,11 +218,9 @@ def _convert_obj(self, obj):
         Returns
         -------
         obj : converted object
-        converter : callable, optional
-            converter to apply after selection
         """
         obj = obj.consolidate()
-        return obj, None
+        return obj
 
     def _get_binner_for_time(self):
         raise AbstractMethodError(self)
@@ -768,7 +767,7 @@ def _resampler_for_grouping(self):
         return PeriodIndexResamplerGroupby
 
     def _convert_obj(self, obj):
-        obj, _ = super(PeriodIndexResampler, self)._convert_obj(obj)
+        obj = super(PeriodIndexResampler, self)._convert_obj(obj)
 
         offset = to_offset(self.freq)
         if offset.n > 1:
@@ -778,17 +777,18 @@ def _convert_obj(self, obj):
             # Cannot have multiple of periods, convert to timestamp
             self.kind = 'timestamp'
 
-        converter = None
         # convert to timestamp
         if not (self.kind is None or self.kind == 'period'):
-            # if periondindex is the actual index obj, just convert it
-            # otherwise, converter callback will be used on selection
             if self.from_selection:
-                converter = lambda x: x.to_timestamp(how=self.convention)
+                # see GH 14008, GH 12871
+                msg = ("Resampling from level= or on= selection"
+                       " with a PeriodIndex is not currently supported,"
+                       " use .set_index(...) to explicitly set index")
+                raise NotImplementedError(msg)
             else:
                 obj = obj.to_timestamp(how=self.convention)
 
-        return obj, converter
+        return obj
 
     def aggregate(self, arg, *args, **kwargs):
         result, how = self._aggregate(arg, *args, **kwargs)