REF: avoid internals in to_csv

jbrockmendel · Oct 8, 2023 · 14a02d8 · 14a02d8
1 parent bfdb4da
commit 14a02d8
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Showing 2 changed files with 21 additions and 2 deletions.
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
@@ -1323,6 +1323,25 @@ def to_string(
                 line_width=line_width,
             )
 
+    def _get_values_for_csv(
+        self,
+        *,
+        float_format: FloatFormatType | None,
+        date_format: str | None,
+        decimal: str,
+        na_rep: str,
+        quoting,  # int csv.QUOTE_FOO from stdlib
+    ) -> Self:
+        # helper used by to_csv
+        mgr = self._mgr.get_values_for_csv(
+            float_format=float_format,
+            date_format=date_format,
+            decimal=decimal,
+            na_rep=na_rep,
+            quoting=quoting,
+        )
+        return self._constructor_from_mgr(mgr, axes=mgr.axes)
+
     # ----------------------------------------------------------------------
 
     @property

diff --git a/pandas/io/formats/csvs.py b/pandas/io/formats/csvs.py
@@ -314,8 +314,8 @@ def _save_chunk(self, start_i: int, end_i: int) -> None:
         slicer = slice(start_i, end_i)
         df = self.obj.iloc[slicer]
 
-        res = df._mgr.get_values_for_csv(**self._number_format)
-        data = [res.iget_values(i) for i in range(len(res.items))]
+        res = df._get_values_for_csv(**self._number_format)
+        data = list(res._iter_column_arrays())
 
         ix = self.data_index[slicer]._format_native_types(**self._number_format)
         libwriters.write_csv_rows(