fixed asfreq in Resampler.asfreq using TDI

Author: discort

doc/source/whatsnew/v0.24.0.txt

@@ -703,6 +703,7 @@ Groupby/Resample/Rolling
 - Multiple bugs in :func:`pandas.core.Rolling.min` with ``closed='left'` and a
   datetime-like index leading to incorrect results and also segfault. (:issue:`21704`)
 - Bug in :meth:`Resampler.apply` when passing postiional arguments to applied func (:issue:`14615`).
+- Bug in :meth:`Resampler.asfreq` when frequency of ``TimedeltaIndex`` is a subperiod of a new frequency (:issue:`13022`).
 
 Sparse
 ^^^^^^

pandas/core/resample.py

@@ -1156,16 +1156,6 @@ def _get_binner_for_time(self):
 
     def _adjust_binner_for_upsample(self, binner):
         """ adjust our binner when upsampling """
-        ax = self.ax
-
-        if is_subperiod(ax.freq, self.freq):
-            # We are actually downsampling
-            # but are in the asfreq path
-            # GH 12926
-            if self.closed == 'right':
-                binner = binner[1:]
-            else:
-                binner = binner[:-1]
         return binner
 
 

pandas/tests/test_resample.py

@@ -626,12 +626,7 @@ def test_asfreq(self, series_and_frame, freq):
         obj = series_and_frame
 
         result = obj.resample(freq).asfreq()
-        if freq == '2D':
-            new_index = obj.index.take(np.arange(0, len(obj.index), 2))
-            new_index.freq = to_offset('2D')
-        else:
-            new_index = self.create_index(obj.index[0], obj.index[-1],
-                                          freq=freq)
+        new_index = self.create_index(obj.index[0], obj.index[-1], freq=freq)
         expected = obj.reindex(new_index)
         assert_almost_equal(result, expected)
 
@@ -2939,6 +2934,17 @@ def test_resample_with_nat(self):
                                                    freq='1S'))
         assert_frame_equal(result, expected)
 
+    def test_resample_as_freq_with_subperiod(self):
+        # GH 13022
+        index = timedelta_range('00:00:00', '00:10:00', freq='5T')
+        df = DataFrame(data={'value': [1, 5, 10]}, index=index)
+        result = df.resample('2T').asfreq()
+        expected_data = {'value': [1, np.nan, np.nan, np.nan, np.nan, 10]}
+        expected = DataFrame(data=expected_data,
+                             index=timedelta_range('00:00:00',
+                                                   '00:10:00', freq='2T'))
+        tm.assert_frame_equal(result, expected)
+
 
 class TestResamplerGrouper(object):