Fix Series.to_string (#721)

* Fix Series.to_string

* float_format

Author: twoertwein

pandas-stubs/core/frame.pyi

@@ -76,7 +76,6 @@ from pandas._typing import (
     Dtype,
     FilePath,
     FillnaOptions,
-    FloatFormatType,
     FormattersType,
     GroupByObjectNonScalar,
     HashableT,
@@ -2161,7 +2160,7 @@ class DataFrame(NDFrame, OpsMixin):
         index: _bool = ...,
         na_rep: _str = ...,
         formatters: FormattersType | None = ...,
-        float_format: FloatFormatType | None = ...,
+        float_format: Callable[[float], str] | None = ...,
         sparsify: _bool | None = ...,
         index_names: _bool = ...,
         justify: _str | None = ...,
@@ -2184,7 +2183,7 @@ class DataFrame(NDFrame, OpsMixin):
         index: _bool = ...,
         na_rep: _str = ...,
         formatters: FormattersType | None = ...,
-        float_format: FloatFormatType | None = ...,
+        float_format: Callable[[float], str] | None = ...,
         sparsify: _bool | None = ...,
         index_names: _bool = ...,
         justify: _str | None = ...,

pandas-stubs/core/series.pyi

@@ -453,38 +453,28 @@ class Series(IndexOpsMixin, NDFrame, Generic[S1]):
         self,
         buf: FilePath | WriteBuffer[str],
         na_rep: _str = ...,
-        formatters=...,
-        float_format=...,
-        sparsify: _bool | None = ...,
-        index_names: _bool = ...,
-        justify: _str | None = ...,
+        float_format: Callable[[float], str] = ...,
+        header: _bool = ...,
+        index: _bool = ...,
+        length: _bool = ...,
+        dtype: _bool = ...,
+        name: _bool = ...,
         max_rows: int | None = ...,
         min_rows: int | None = ...,
-        max_cols: int | None = ...,
-        show_dimensions: _bool = ...,
-        decimal: _str = ...,
-        line_width: int | None = ...,
-        max_colwidth: int | None = ...,
-        encoding: _str | None = ...,
     ) -> None: ...
     @overload
     def to_string(
         self,
         buf: None = ...,
         na_rep: _str = ...,
-        formatters=...,
-        float_format=...,
-        sparsify: _bool | None = ...,
-        index_names: _bool = ...,
-        justify: _str | None = ...,
+        float_format: Callable[[float], str] = ...,
+        header: _bool = ...,
+        index: _bool = ...,
+        length: _bool = ...,
+        dtype: _bool = ...,
+        name: _bool = ...,
         max_rows: int | None = ...,
         min_rows: int | None = ...,
-        max_cols: int | None = ...,
-        show_dimensions: _bool = ...,
-        decimal: _str = ...,
-        line_width: int | None = ...,
-        max_colwidth: int | None = ...,
-        encoding: _str | None = ...,
     ) -> _str: ...
     @overload
     def to_json(

tests/test_series.py

@@ -1989,3 +1989,17 @@ def test_groupby_diff() -> None:
     # GH 658
     s = pd.Series([1, 2, 3, np.nan])
     check(assert_type(s.groupby(level=0).diff(), pd.Series), pd.Series)
+
+
+def test_to_string() -> None:
+    # GH 720
+    s = pd.Series([1])
+    check(
+        assert_type(
+            s.to_string(
+                index=False, header=False, length=False, dtype=False, name=False
+            ),
+            str,
+        ),
+        str,
+    )