ENH: Let to_feather accept index and non string column names

doc/source/whatsnew/v2.1.0.rst

@@ -29,7 +29,7 @@ enhancement2
 Other enhancements
 ^^^^^^^^^^^^^^^^^^
 - Improve error message when setting :class:`DataFrame` with wrong number of columns through :meth:`DataFrame.isetitem` (:issue:`51701`)
--
+- Let :meth:`DataFrame.to_feather` accept a non-default :class:`Index` and non-string column names (:issue:`51787`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_210.notable_bug_fixes:

pandas/io/feather_format.py

@@ -22,10 +22,7 @@
     arrays,
     get_option,
 )
-from pandas.core.api import (
-    DataFrame,
-    RangeIndex,
-)
+from pandas.core.api import DataFrame
 from pandas.core.shared_docs import _shared_docs
 
 from pandas.io.common import get_handle
@@ -60,39 +57,6 @@ def to_feather(
     if not isinstance(df, DataFrame):
         raise ValueError("feather only support IO with DataFrames")
 
-    valid_types = {"string", "unicode"}
-
-    # validate index
-    # --------------
-
-    # validate that we have only a default index
-    # raise on anything else as we don't serialize the index
-
-    if not df.index.dtype == "int64":
-        typ = type(df.index)
-        raise ValueError(
-            f"feather does not support serializing {typ} "
-            "for the index; you can .reset_index() to make the index into column(s)"
-        )
-
-    if not df.index.equals(RangeIndex.from_range(range(len(df)))):
-        raise ValueError(
-            "feather does not support serializing a non-default index for the index; "
-            "you can .reset_index() to make the index into column(s)"
-        )
-
-    if df.index.name is not None:
-        raise ValueError(
-            "feather does not serialize index meta-data on a default index"
-        )
-
-    # validate columns
-    # ----------------
-
-    # must have value column names (strings only)
-    if df.columns.inferred_type not in valid_types:
-        raise ValueError("feather must have string column names")
-
     with get_handle(
         path, "wb", storage_options=storage_options, is_text=False
     ) as handles:

pandas/tests/io/test_feather.py

@@ -34,7 +34,7 @@ def check_external_error_on_write(self, df):
 
     def check_round_trip(self, df, expected=None, write_kwargs={}, **read_kwargs):
         if expected is None:
-            expected = df
+            expected = df.copy()
 
         with tm.ensure_clean() as path:
             to_feather(df, path, **write_kwargs)
@@ -94,11 +94,6 @@ def test_duplicate_columns(self):
         df = pd.DataFrame(np.arange(12).reshape(4, 3), columns=list("aaa")).copy()
         self.check_external_error_on_write(df)
 
-    def test_stringify_columns(self):
-        df = pd.DataFrame(np.arange(12).reshape(4, 3)).copy()
-        msg = "feather must have string column names"
-        self.check_error_on_write(df, ValueError, msg)
-
     def test_read_columns(self):
         # GH 24025
         df = pd.DataFrame(
@@ -128,37 +123,6 @@ def test_rw_use_threads(self):
         self.check_round_trip(df, use_threads=True)
         self.check_round_trip(df, use_threads=False)
 
-    def test_write_with_index(self):
-        df = pd.DataFrame({"A": [1, 2, 3]})
-        self.check_round_trip(df)
-
-        msg = (
-            r"feather does not support serializing .* for the index; "
-            r"you can \.reset_index\(\) to make the index into column\(s\)"
-        )
-        # non-default index
-        for index in [
-            [2, 3, 4],
-            pd.date_range("20130101", periods=3),
-            list("abc"),
-            [1, 3, 4],
-            pd.MultiIndex.from_tuples([("a", 1), ("a", 2), ("b", 1)]),
-        ]:
-            df.index = index
-            self.check_error_on_write(df, ValueError, msg)
-
-        # index with meta-data
-        df.index = [0, 1, 2]
-        df.index.name = "foo"
-        msg = "feather does not serialize index meta-data on a default index"
-        self.check_error_on_write(df, ValueError, msg)
-
-        # column multi-index
-        df.index = [0, 1, 2]
-        df.columns = pd.MultiIndex.from_tuples([("a", 1)])
-        msg = "feather must have string column names"
-        self.check_error_on_write(df, ValueError, msg)
-
     def test_path_pathlib(self):
         df = tm.makeDataFrame().reset_index()
         result = tm.round_trip_pathlib(df.to_feather, read_feather)
@@ -250,3 +214,7 @@ def test_read_json_nullable(self, string_storage, dtype_backend, option):
             )
 
         tm.assert_frame_equal(result, expected)
+
+    def test_int_columns_and_index(self):
+        df = pd.DataFrame({"a": [1, 2, 3]}, index=pd.Index([3, 4, 5], name="test"))
+        self.check_round_trip(df)