PERF: Return a RangeIndex from __getitem__ with a bool mask when possible

doc/source/whatsnew/v3.0.0.rst

@@ -167,6 +167,7 @@ Removal of prior version deprecations/changes
 
 Performance improvements
 ~~~~~~~~~~~~~~~~~~~~~~~~
+- :meth:`Series.str.extract` returns a :class:`RangeIndex` columns instead of an :class:`Index` column when possible (:issue:`57542`)
 - Performance improvement in :class:`DataFrame` when ``data`` is a ``dict`` and ``columns`` is specified (:issue:`24368`)
 - Performance improvement in :meth:`DataFrame.join` for sorted but non-unique indexes (:issue:`56941`)
 - Performance improvement in :meth:`DataFrame.join` when left and/or right are non-unique and ``how`` is ``"left"``, ``"right"``, or ``"inner"`` (:issue:`56817`)
@@ -175,11 +176,11 @@ Performance improvements
 - Performance improvement in :meth:`Index.join` by propagating cached attributes in cases where the result matches one of the inputs (:issue:`57023`)
 - Performance improvement in :meth:`Index.take` when ``indices`` is a full range indexer from zero to length of index (:issue:`56806`)
 - Performance improvement in :meth:`MultiIndex.equals` for equal length indexes (:issue:`56990`)
+- Performance improvement in :meth:`RangeIndex.__getitem__` with a boolean mask returning a :class:`RangeIndex` instead of a :class:`Index` when possible. (:issue:`57588`)
 - Performance improvement in :meth:`RangeIndex.append` when appending the same index (:issue:`57252`)
 - Performance improvement in :meth:`RangeIndex.take` returning a :class:`RangeIndex` instead of a :class:`Index` when possible. (:issue:`57445`)
-- Performance improvement in indexing operations for string dtypes (:issue:`56997`)
-- :meth:`Series.str.extract` returns a :class:`RangeIndex` columns instead of an :class:`Index` column when possible (:issue:`?``)
 - Performance improvement in ``DataFrameGroupBy.__len__`` and ``SeriesGroupBy.__len__`` (:issue:`57595`)
+- Performance improvement in indexing operations for string dtypes (:issue:`56997`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_300.bug_fixes:

pandas/core/indexes/range.py

@@ -29,6 +29,7 @@
     doc,
 )
 
+from pandas.core.dtypes.base import ExtensionDtype
 from pandas.core.dtypes.common import (
     ensure_platform_int,
     ensure_python_int,
@@ -42,6 +43,7 @@
 from pandas.core import ops
 import pandas.core.common as com
 from pandas.core.construction import extract_array
+from pandas.core.indexers import check_array_indexer
 import pandas.core.indexes.base as ibase
 from pandas.core.indexes.base import (
     Index,
@@ -1048,6 +1050,18 @@ def __getitem__(self, key):
                 "and integer or boolean "
                 "arrays are valid indices"
             )
+        elif com.is_bool_indexer(key):
+            if isinstance(getattr(key, "dtype", None), ExtensionDtype):
+                np_key = key.to_numpy(dtype=bool, na_value=False)
+            else:
+                np_key = np.asarray(key, dtype=bool)
+            check_array_indexer(self._range, np_key)  # type: ignore[arg-type]
+            # Short circuit potential _shallow_copy check
+            if np_key.all():
+                return self._simple_new(self._range, name=self.name)
+            elif not np_key.any():
+                return self._simple_new(_empty_range, name=self.name)
+            return self.take(np.flatnonzero(np_key))
         return super().__getitem__(key)
 
     def _getitem_slice(self, slobj: slice) -> Self:

pandas/tests/indexes/ranges/test_range.py

@@ -623,3 +623,41 @@ def test_append_one_nonempty_preserve_step():
     expected = RangeIndex(0, -1, -1)
     result = RangeIndex(0).append([expected])
     tm.assert_index_equal(result, expected, exact=True)
+
+
+def test_getitem_boolmask_all_true():
+    ri = RangeIndex(3, name="foo")
+    expected = ri.copy()
+    result = ri[[True] * 3]
+    tm.assert_index_equal(result, expected, exact=True)
+
+
+def test_getitem_boolmask_all_false():
+    ri = RangeIndex(3, name="foo")
+    result = ri[[False] * 3]
+    expected = RangeIndex(0, name="foo")
+    tm.assert_index_equal(result, expected, exact=True)
+
+
+def test_getitem_boolmask_returns_rangeindex():
+    ri = RangeIndex(3, name="foo")
+    result = ri[[False, True, True]]
+    expected = RangeIndex(1, 3, name="foo")
+    tm.assert_index_equal(result, expected, exact=True)
+
+    result = ri[[True, False, True]]
+    expected = RangeIndex(0, 3, 2, name="foo")
+    tm.assert_index_equal(result, expected, exact=True)
+
+
+def test_getitem_boolmask_returns_index():
+    ri = RangeIndex(4, name="foo")
+    result = ri[[True, True, False, True]]
+    expected = Index([0, 1, 3], name="foo")
+    tm.assert_index_equal(result, expected)
+
+
+def test_getitem_boolmask_wrong_length():
+    ri = RangeIndex(4, name="foo")
+    with pytest.raises(IndexError, match="Boolean index has wrong length"):
+        ri[[True]]

pandas/tests/io/pytables/test_append.py

@@ -132,6 +132,8 @@ def test_append_series(setup_path):
 
         # select on the index and values
         expected = ns[(ns > 70) & (ns.index < 90)]
+        # Reading/writing RangeIndex info is not supported yet
+        expected.index = Index(expected.index._data)
         result = store.select("ns", "foo>70 and index<90")
         tm.assert_series_equal(result, expected, check_index_type=True)