DEPR: deprecated nonkeyword arguments in to_parquet

doc/source/whatsnew/v2.2.0.rst

@@ -97,6 +97,7 @@ Deprecations
 - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_json` except ``path_or_buf``. (:issue:`54229`)
 - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_latex` except ``buf``. (:issue:`54229`)
 - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_markdown` except ``buf``. (:issue:`54229`)
+- Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_parquet` except ``path``. (:issue:`54229`)
 - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_pickle` except ``path``. (:issue:`54229`)
 - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_string` except ``buf``. (:issue:`54229`)
 - Deprecated not passing a tuple to :class:`DataFrameGroupBy.get_group` or :class:`SeriesGroupBy.get_group` when grouping by a length-1 list-like (:issue:`25971`)

pandas/core/frame.py

@@ -2878,6 +2878,9 @@ def to_parquet(
     ) -> None:
         ...
 
+    @deprecate_nonkeyword_arguments(
+        version="3.0", allowed_args=["self", "path"], name="to_parquet"
+    )
     @doc(storage_options=_shared_docs["storage_options"])
     def to_parquet(
         self,

pandas/tests/io/test_parquet.py

@@ -359,6 +359,18 @@ def test_cross_engine_fp_pa(df_cross_compat, pa, fp):
         tm.assert_frame_equal(result, df[["a", "d"]])
 
 
+def test_parquet_pos_args_deprecation():
+    # GH-54229
+    df = pd.DataFrame({"a": [1, 2, 3]})
+    msg = (
+        r"Starting with pandas version 3.0 all arguments of to_parquet except for the "
+        r"argument 'path' will be keyword-only."
+    )
+    with tm.assert_produces_warning(FutureWarning, match=msg, check_stacklevel=False):
+        buffer = BytesIO()
+        df.to_parquet(buffer, "auto")
+
+
 class Base:
     def check_error_on_write(self, df, engine, exc, err_msg):
         # check that we are raising the exception on writing
@@ -998,7 +1010,7 @@ def test_filter_row_groups(self, pa):
         pytest.importorskip("pyarrow")
         df = pd.DataFrame({"a": list(range(0, 3))})
         with tm.ensure_clean() as path:
-            df.to_parquet(path, pa)
+            df.to_parquet(path, engine=pa)
             result = read_parquet(
                 path, pa, filters=[("a", "==", 0)], use_legacy_dataset=False
             )
@@ -1011,7 +1023,7 @@ def test_read_parquet_manager(self, pa, using_array_manager):
         )
 
         with tm.ensure_clean() as path:
-            df.to_parquet(path, pa)
+            df.to_parquet(path, engine=pa)
             result = read_parquet(path, pa)
         if using_array_manager:
             assert isinstance(result._mgr, pd.core.internals.ArrayManager)
@@ -1177,7 +1189,7 @@ def test_filter_row_groups(self, fp):
         d = {"a": list(range(0, 3))}
         df = pd.DataFrame(d)
         with tm.ensure_clean() as path:
-            df.to_parquet(path, fp, compression=None, row_group_offsets=1)
+            df.to_parquet(path, engine=fp, compression=None, row_group_offsets=1)
             result = read_parquet(path, fp, filters=[("a", "==", 0)])
         assert len(result) == 1