adding str to read_excel index_col, resolves #809 (#914)

Co-authored-by: Laurent Mutricy <[email protected]>

Author: mutricyl

pandas-stubs/io/excel/_base.pyi

@@ -49,7 +49,7 @@ def read_excel(
     *,
     header: int | Sequence[int] | None = ...,
     names: ListLikeHashable | None = ...,
-    index_col: int | Sequence[int] | None = ...,
+    index_col: int | Sequence[int] | str | None = ...,
     usecols: str | UsecolsArgType = ...,
     dtype: str | Dtype | Mapping[str, str | Dtype] | None = ...,
     engine: ExcelReadEngine | None = ...,
@@ -91,7 +91,7 @@ def read_excel(
     *,
     header: int | Sequence[int] | None = ...,
     names: ListLikeHashable | None = ...,
-    index_col: int | Sequence[int] | None = ...,
+    index_col: int | Sequence[int] | str | None = ...,
     usecols: str | UsecolsArgType = ...,
     dtype: str | Dtype | Mapping[str, str | Dtype] | None = ...,
     engine: ExcelReadEngine | None = ...,
@@ -134,7 +134,7 @@ def read_excel(  # type: ignore[misc]
     *,
     header: int | Sequence[int] | None = ...,
     names: ListLikeHashable | None = ...,
-    index_col: int | Sequence[int] | None = ...,
+    index_col: int | Sequence[int] | str | None = ...,
     usecols: str | UsecolsArgType = ...,
     dtype: str | Dtype | Mapping[str, str | Dtype] | None = ...,
     engine: ExcelReadEngine | None = ...,
@@ -176,7 +176,7 @@ def read_excel(
     *,
     header: int | Sequence[int] | None = ...,
     names: ListLikeHashable | None = ...,
-    index_col: int | Sequence[int] | None = ...,
+    index_col: int | Sequence[int] | str | None = ...,
     usecols: str | UsecolsArgType = ...,
     dtype: str | Dtype | Mapping[str, str | Dtype] | None = ...,
     engine: ExcelReadEngine | None = ...,

tests/test_io.py

@@ -1558,3 +1558,21 @@ def test_added_date_format() -> None:
             ),
             pd.DataFrame,
         )
+
+
+def test_read_excel_index_col() -> None:
+    with ensure_clean(".xlsx") as path:
+        pd.DataFrame(
+            data={
+                "foo": [1, 3],
+                "bar": [2, 4],
+            }
+        ).to_excel(path)
+
+        check(
+            assert_type(
+                pd.read_excel(path, index_col="bar"),
+                pd.DataFrame,
+            ),
+            pd.DataFrame,
+        )