Backport PR pandas-dev#48696: REGR: to_hdf raising AssertionError with boolean index

Author: phofl

doc/source/whatsnew/v1.5.1.rst

@@ -24,7 +24,7 @@ Fixed regressions
 
 Bug fixes
 ~~~~~~~~~
--
+- Bug in :meth:`DataFrame.to_hdf` raising ``AssertionError`` with boolean index (:issue:`48667`)
 -
 
 .. ---------------------------------------------------------------------------

pandas/io/pytables.py

@@ -63,6 +63,7 @@
 
 from pandas.core.dtypes.common import (
     ensure_object,
+    is_bool_dtype,
     is_categorical_dtype,
     is_complex_dtype,
     is_datetime64_dtype,
@@ -4893,7 +4894,11 @@ def _convert_index(name: str, index: Index, encoding: str, errors: str) -> Index
     kind = _dtype_to_kind(dtype_name)
     atom = DataIndexableCol._get_atom(converted)
 
-    if isinstance(index, Int64Index) or needs_i8_conversion(index.dtype):
+    if (
+        isinstance(index, Int64Index)
+        or needs_i8_conversion(index.dtype)
+        or is_bool_dtype(index.dtype)
+    ):
         # Includes Int64Index, RangeIndex, DatetimeIndex, TimedeltaIndex, PeriodIndex,
         #  in which case "kind" is "integer", "integer", "datetime64",
         #  "timedelta64", and "integer", respectively.
@@ -4956,7 +4961,7 @@ def _unconvert_index(data, kind: str, encoding: str, errors: str) -> np.ndarray
             index = np.asarray([date.fromordinal(v) for v in data], dtype=object)
         except (ValueError):
             index = np.asarray([date.fromtimestamp(v) for v in data], dtype=object)
-    elif kind in ("integer", "float"):
+    elif kind in ("integer", "float", "bool"):
         index = np.asarray(data)
     elif kind in ("string"):
         index = _unconvert_string_array(

pandas/tests/io/pytables/test_store.py

@@ -1026,3 +1026,16 @@ def test_hdfstore_strides(setup_path):
     with ensure_clean_store(setup_path) as store:
         store.put("df", df)
         assert df["a"].values.strides == store["df"]["a"].values.strides
+
+
+def test_store_bool_index(setup_path):
+    # GH#48667
+    df = DataFrame([[1]], columns=[True], index=Index([False], dtype="bool"))
+    expected = df.copy()
+
+    # # Test to make sure defaults are to not drop.
+    # # Corresponding to Issue 9382
+    with ensure_clean_path(setup_path) as path:
+        df.to_hdf(path, "a")
+        result = read_hdf(path, "a")
+        tm.assert_frame_equal(expected, result)