update comments for _adjust_binner_for_upsample

Author: discort

pandas/core/resample.py

@@ -963,7 +963,10 @@ def _downsample(self, how, **kwargs):
         return self._wrap_result(result)
 
     def _adjust_binner_for_upsample(self, binner):
-        """ adjust our binner when upsampling """
+        """
+        Adjust our binner when upsampling.
+        The range of a new index should not be outside specified range
+        """
         if self.closed == 'right':
             binner = binner[1:]
         else:
@@ -1156,7 +1159,11 @@ def _get_binner_for_time(self):
         return self.groupby._get_time_delta_bins(self.ax)
 
     def _adjust_binner_for_upsample(self, binner):
-        """ adjust our binner when upsampling """
+        """
+        Adjust our binner when upsampling.
+        The range of a new index is allowed to be greater than original range
+        so we don't need to change the length of a binner, GH 13022
+        """
         return binner
 
 

pandas/tests/test_resample.py

@@ -26,7 +26,6 @@
 from pandas.compat import range, lrange, zip, OrderedDict
 from pandas.errors import UnsupportedFunctionCall
 import pandas.tseries.offsets as offsets
-from pandas.tseries.frequencies import to_offset
 from pandas.tseries.offsets import Minute, BDay
 
 from pandas.core.groupby.groupby import DataError