CLN: int slice on Index[float] as positional (#58646)

Author: mroeschke

doc/source/whatsnew/v0.13.0.rst

@@ -345,7 +345,6 @@ Float64Index API change
   .. ipython:: python
      :okwarning:
 
-     s[2:4]
      s.loc[2:4]
      s.iloc[2:4]
 

doc/source/whatsnew/v3.0.0.rst

@@ -225,6 +225,7 @@ Removal of prior version deprecations/changes
 - All arguments except ``name`` in :meth:`Index.rename` are now keyword only (:issue:`56493`)
 - All arguments except the first ``path``-like argument in IO writers are now keyword only (:issue:`54229`)
 - Changed behavior of :meth:`Series.__getitem__` and :meth:`Series.__setitem__` to always treat integer keys as labels, never as positional, consistent with :class:`DataFrame` behavior (:issue:`50617`)
+- Changed behavior of :meth:`Series.__getitem__`, :meth:`Series.__setitem__`, :meth:`DataFrame.__getitem__`, :meth:`DataFrame.__setitem__` with an integer slice on objects with a floating-dtype index. This is now treated as *positional* indexing (:issue:`49612`)
 - Disallow a callable argument to :meth:`Series.iloc` to return a ``tuple`` (:issue:`53769`)
 - Disallow allowing logical operations (``||``, ``&``, ``^``) between pandas objects and dtype-less sequences (e.g. ``list``, ``tuple``); wrap the objects in :class:`Series`, :class:`Index`, or ``np.array`` first instead (:issue:`52264`)
 - Disallow automatic casting to object in :class:`Series` logical operations (``&``, ``^``, ``||``) between series with mismatched indexes and dtypes other than ``object`` or ``bool`` (:issue:`52538`)

pandas/core/indexes/base.py

@@ -4005,25 +4005,6 @@ def _convert_slice_indexer(self, key: slice, kind: Literal["loc", "getitem"]):
 
         # TODO(GH#50617): once Series.__[gs]etitem__ is removed we should be able
         #  to simplify this.
-        if lib.is_np_dtype(self.dtype, "f"):
-            # We always treat __getitem__ slicing as label-based
-            # translate to locations
-            if kind == "getitem" and is_index_slice and not start == stop and step != 0:
-                # exclude step=0 from the warning because it will raise anyway
-                # start/stop both None e.g. [:] or [::-1] won't change.
-                # exclude start==stop since it will be empty either way, or
-                # will be [:] or [::-1] which won't change
-                warnings.warn(
-                    # GH#49612
-                    "The behavior of obj[i:j] with a float-dtype index is "
-                    "deprecated. In a future version, this will be treated as "
-                    "positional instead of label-based. For label-based slicing, "
-                    "use obj.loc[i:j] instead",
-                    FutureWarning,
-                    stacklevel=find_stack_level(),
-                )
-            return self.slice_indexer(start, stop, step)
-
         if kind == "getitem":
             # called from the getitem slicers, validate that we are in fact integers
             if is_index_slice:

pandas/tests/frame/indexing/test_indexing.py

@@ -724,6 +724,14 @@ def test_getitem_setitem_boolean_multi(self):
         expected.loc[[0, 2], [1]] = 5
         tm.assert_frame_equal(df, expected)
 
+    def test_getitem_float_label_positional(self):
+        # GH 53338
+        index = Index([1.5, 2])
+        df = DataFrame(range(2), index=index)
+        result = df[1:2]
+        expected = DataFrame([1], index=[2.0])
+        tm.assert_frame_equal(result, expected)
+
     def test_getitem_setitem_float_labels(self):
         index = Index([1.5, 2, 3, 4, 5])
         df = DataFrame(np.random.default_rng(2).standard_normal((5, 5)), index=index)
@@ -748,12 +756,6 @@ def test_getitem_setitem_float_labels(self):
         expected = df.iloc[0:2]
         tm.assert_frame_equal(result, expected)
 
-        expected = df.iloc[0:2]
-        msg = r"The behavior of obj\[i:j\] with a float-dtype index"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            result = df[1:2]
-        tm.assert_frame_equal(result, expected)
-
         # #2727
         index = Index([1.0, 2.5, 3.5, 4.5, 5.0])
         df = DataFrame(np.random.default_rng(2).standard_normal((5, 5)), index=index)

pandas/tests/indexing/test_floats.py

@@ -488,24 +488,12 @@ def test_floating_misc(self, indexer_sl):
         for fancy_idx in [[5, 0], np.array([5, 0])]:
             tm.assert_series_equal(indexer_sl(s)[fancy_idx], expected)
 
-        warn = FutureWarning if indexer_sl is tm.setitem else None
-        msg = r"The behavior of obj\[i:j\] with a float-dtype index"
-
         # all should return the same as we are slicing 'the same'
-        with tm.assert_produces_warning(warn, match=msg):
-            result1 = indexer_sl(s)[2:5]
         result2 = indexer_sl(s)[2.0:5.0]
         result3 = indexer_sl(s)[2.0:5]
         result4 = indexer_sl(s)[2.1:5]
-        tm.assert_series_equal(result1, result2)
-        tm.assert_series_equal(result1, result3)
-        tm.assert_series_equal(result1, result4)
-
-        expected = Series([1, 2], index=[2.5, 5.0])
-        with tm.assert_produces_warning(warn, match=msg):
-            result = indexer_sl(s)[2:5]
-
-        tm.assert_series_equal(result, expected)
+        tm.assert_series_equal(result2, result3)
+        tm.assert_series_equal(result2, result4)
 
         # list selection
         result1 = indexer_sl(s)[[0.0, 5, 10]]