BUG: to_hdf and HDFStore for subclasses

pandas/io/pytables.py

@@ -1646,8 +1646,10 @@ def error(t):
                         "nor a value are passed"
                     )
             else:
-                _TYPE_MAP = {Series: "series", DataFrame: "frame"}
-                pt = _TYPE_MAP[type(value)]
+                if isinstance(value, Series):
+                    pt = "series"
+                else:
+                    pt = "frame"
 
                 # we are actually a table
                 if format == "table":

pandas/tests/io/pytables/test_subclass.py

@@ -0,0 +1,44 @@
+import numpy as np
+
+from pandas import DataFrame, Series
+import pandas._testing as tm
+from pandas.tests.io.pytables.common import ensure_clean_path
+
+from pandas.io.pytables import HDFStore, read_hdf
+
+
+class TestHDFStoreSubclass:
+    # GH 33748
+    def test_supported_for_subclass_dataframe(self):
+        data = {"a": [1, 2], "b": [3, 4]}
+        sdf = tm.SubclassedDataFrame(data, dtype=np.intp)
+
+        expected = DataFrame(data, dtype=np.intp)
+
+        with ensure_clean_path("temp.h5") as path:
+            sdf.to_hdf(path, "df")
+            result = read_hdf(path, "df")
+            tm.assert_frame_equal(result, expected)
+
+        with ensure_clean_path("temp.h5") as path:
+            with HDFStore(path) as store:
+                store.put("df", sdf)
+            result = read_hdf(path, "df")
+            tm.assert_frame_equal(result, expected)
+
+    def test_supported_for_subclass_series(self):
+        data = [1, 2, 3]
+        sser = tm.SubclassedSeries(data, dtype=np.intp)
+
+        expected = Series(data, dtype=np.intp)
+
+        with ensure_clean_path("temp.h5") as path:
+            sser.to_hdf(path, "ser")
+            result = read_hdf(path, "ser")
+            tm.assert_series_equal(result, expected)
+
+        with ensure_clean_path("temp.h5") as path:
+            with HDFStore(path) as store:
+                store.put("ser", sser)
+            result = read_hdf(path, "ser")
+            tm.assert_series_equal(result, expected)