CLN: trim unreachable indexing code (#31768)

Author: jbrockmendel

pandas/core/frame.py

@@ -3011,17 +3011,12 @@ def _set_value(self, index, col, value, takeable: bool = False):
         col : column label
         value : scalar
         takeable : interpret the index/col as indexers, default False
-
-        Returns
-        -------
-        DataFrame
-            If label pair is contained, will be reference to calling DataFrame,
-            otherwise a new object.
         """
         try:
             if takeable is True:
                 series = self._iget_item_cache(col)
-                return series._set_value(index, value, takeable=True)
+                series._set_value(index, value, takeable=True)
+                return
 
             series = self._get_item_cache(col)
             engine = self.index._engine
@@ -3031,7 +3026,6 @@ def _set_value(self, index, col, value, takeable: bool = False):
             series._values[loc] = value
             # Note: trying to use series._set_value breaks tests in
             #  tests.frame.indexing.test_indexing and tests.indexing.test_partial
-            return self
         except (KeyError, TypeError):
             # set using a non-recursive method & reset the cache
             if takeable:
@@ -3040,8 +3034,6 @@ def _set_value(self, index, col, value, takeable: bool = False):
                 self.loc[index, col] = value
             self._item_cache.pop(col, None)
 
-            return self
-
     def _ensure_valid_index(self, value):
         """
         Ensure that if we don't have an index, that we can create one from the

pandas/core/series.py

@@ -905,7 +905,7 @@ def _get_with(self, key):
                         return self._get_values(key)
                 raise
 
-        if not isinstance(key, (list, np.ndarray, Series, Index)):
+        if not isinstance(key, (list, np.ndarray, ExtensionArray, Series, Index)):
             key = list(key)
 
         if isinstance(key, Index):
@@ -1004,8 +1004,6 @@ def __setitem__(self, key, value):
 
         try:
             self._set_with_engine(key, value)
-        except com.SettingWithCopyError:
-            raise
         except (KeyError, ValueError):
             values = self._values
             if is_integer(key) and not self.index.inferred_type == "integer":
@@ -1014,9 +1012,6 @@ def __setitem__(self, key, value):
                 self[:] = value
             else:
                 self.loc[key] = value
-        except InvalidIndexError:
-            # e.g. slice
-            self._set_with(key, value)
 
         except TypeError as e:
             if isinstance(key, tuple) and not isinstance(self.index, MultiIndex):
@@ -1087,7 +1082,7 @@ def _set_with(self, key, value):
 
     def _set_labels(self, key, value):
         key = com.asarray_tuplesafe(key)
-        indexer = self.index.get_indexer(key)
+        indexer: np.ndarray = self.index.get_indexer(key)
         mask = indexer == -1
         if mask.any():
             raise ValueError(f"{key[mask]} not contained in the index")
@@ -1113,12 +1108,6 @@ def _set_value(self, label, value, takeable: bool = False):
         value : object
             Scalar value.
         takeable : interpret the index as indexers, default False
-
-        Returns
-        -------
-        Series
-            If label is contained, will be reference to calling Series,
-            otherwise a new object.
         """
         try:
             if takeable:
@@ -1132,8 +1121,6 @@ def _set_value(self, label, value, takeable: bool = False):
             # set using a non-recursive method
             self.loc[label] = value
 
-        return self
-
     # ----------------------------------------------------------------------
     # Unsorted
 

pandas/tests/frame/indexing/test_indexing.py

@@ -1377,28 +1377,28 @@ def test_set_value(self, float_frame):
     def test_set_value_resize(self, float_frame):
 
         res = float_frame._set_value("foobar", "B", 0)
-        assert res is float_frame
-        assert res.index[-1] == "foobar"
-        assert res._get_value("foobar", "B") == 0
+        assert res is None
+        assert float_frame.index[-1] == "foobar"
+        assert float_frame._get_value("foobar", "B") == 0
 
         float_frame.loc["foobar", "qux"] = 0
         assert float_frame._get_value("foobar", "qux") == 0
 
         res = float_frame.copy()
-        res3 = res._set_value("foobar", "baz", "sam")
-        assert res3["baz"].dtype == np.object_
+        res._set_value("foobar", "baz", "sam")
+        assert res["baz"].dtype == np.object_
 
         res = float_frame.copy()
-        res3 = res._set_value("foobar", "baz", True)
-        assert res3["baz"].dtype == np.object_
+        res._set_value("foobar", "baz", True)
+        assert res["baz"].dtype == np.object_
 
         res = float_frame.copy()
-        res3 = res._set_value("foobar", "baz", 5)
-        assert is_float_dtype(res3["baz"])
-        assert isna(res3["baz"].drop(["foobar"])).all()
+        res._set_value("foobar", "baz", 5)
+        assert is_float_dtype(res["baz"])
+        assert isna(res["baz"].drop(["foobar"])).all()
         msg = "could not convert string to float: 'sam'"
         with pytest.raises(ValueError, match=msg):
-            res3._set_value("foobar", "baz", "sam")
+            res._set_value("foobar", "baz", "sam")
 
     def test_set_value_with_index_dtype_change(self):
         df_orig = DataFrame(np.random.randn(3, 3), index=range(3), columns=list("ABC"))

pandas/tests/series/indexing/test_datetime.py

@@ -73,17 +73,13 @@ def test_series_set_value():
     dates = [datetime(2001, 1, 1), datetime(2001, 1, 2)]
     index = DatetimeIndex(dates)
 
-    s = Series(dtype=object)._set_value(dates[0], 1.0)
-    s2 = s._set_value(dates[1], np.nan)
+    s = Series(dtype=object)
+    s._set_value(dates[0], 1.0)
+    s._set_value(dates[1], np.nan)
 
     expected = Series([1.0, np.nan], index=index)
 
-    tm.assert_series_equal(s2, expected)
-
-    # FIXME: dont leave commented-out
-    # s = Series(index[:1], index[:1])
-    # s2 = s._set_value(dates[1], index[1])
-    # assert s2.values.dtype == 'M8[ns]'
+    tm.assert_series_equal(s, expected)
 
 
 @pytest.mark.slow

pandas/tests/series/indexing/test_indexing.py

@@ -375,15 +375,15 @@ def test_setitem_dtypes():
 def test_set_value(datetime_series, string_series):
     idx = datetime_series.index[10]
     res = datetime_series._set_value(idx, 0)
-    assert res is datetime_series
+    assert res is None
     assert datetime_series[idx] == 0
 
     # equiv
     s = string_series.copy()
     res = s._set_value("foobar", 0)
-    assert res is s
-    assert res.index[-1] == "foobar"
-    assert res["foobar"] == 0
+    assert res is None
+    assert s.index[-1] == "foobar"
+    assert s["foobar"] == 0
 
     s = string_series.copy()
     s.loc["foobar"] = 0