BUG: Sampling over selected groupbys does not reflect the selection

Author: wjsi

doc/source/whatsnew/v1.3.1.rst

@@ -25,7 +25,7 @@ Fixed regressions
 
 Bug fixes
 ~~~~~~~~~
--
+- Bug in :meth:`DataFrame.shift` where TypeError occurred when shifting DataFrame created by concatenation of slices and fills with values (:issue:`42401`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/core/internals/managers.py

@@ -386,10 +386,12 @@ def shift(self: T, periods: int, axis: int, fill_value) -> T:
             # We only get here with fill_value not-lib.no_default
             ncols = self.shape[0]
             if periods > 0:
-                indexer = [-1] * periods + list(range(ncols - periods))
+                indexer = np.concatenate(
+                    [np.repeat(-1, periods), np.arange(ncols - periods)]
+                )
             else:
                 nper = abs(periods)
-                indexer = list(range(nper, ncols)) + [-1] * nper
+                indexer = np.concatenate([np.arange(nper, ncols), np.repeat(-1, nper)])
             result = self.reindex_indexer(
                 self.items,
                 indexer,

pandas/tests/frame/methods/test_shift.py

@@ -183,6 +183,30 @@ def test_shift_axis1_multiple_blocks(self, using_array_manager):
 
         tm.assert_frame_equal(result, expected)
 
+        # GH#42401
+        df3 = pd.concat([df1.iloc[:4, 1:3], df2.iloc[:4, :]], axis=1)
+        result = df3.shift(2, axis=1, fill_value=0)
+        if not using_array_manager:
+            assert len(df3._mgr.blocks) == 2
+
+        expected = df3.take([-1, -1, 0, 1], axis=1)
+        expected.iloc[:, :2] = 0
+        expected.columns = df3.columns
+
+        tm.assert_frame_equal(result, expected)
+
+        # Case with periods < 0
+        df3 = pd.concat([df1.iloc[:4, 1:3], df2.iloc[:4, :]], axis=1)
+        result = df3.shift(-2, axis=1, fill_value=0)
+        if not using_array_manager:
+            assert len(df3._mgr.blocks) == 2
+
+        expected = df3.take([2, 3, -1, -1], axis=1)
+        expected.iloc[:, -2:] = 0
+        expected.columns = df3.columns
+
+        tm.assert_frame_equal(result, expected)
+
     @pytest.mark.filterwarnings("ignore:tshift is deprecated:FutureWarning")
     def test_tshift(self, datetime_frame):
         # TODO: remove this test when tshift deprecation is enforced