Fix read_excel dtypes and converters to use Mapping not dict (#503)

Author: Dr-Irv

pandas-stubs/io/excel/_base.pyi

@@ -2,6 +2,7 @@ from collections.abc import (
     Callable,
     Hashable,
     Iterable,
+    Mapping,
     Sequence,
 )
 from types import TracebackType
@@ -41,9 +42,9 @@ def read_excel(
     names: list[str] | None = ...,
     index_col: int | Sequence[int] | None = ...,
     usecols: Sequence[int] | Sequence[str] | Callable[[str], bool] | None = ...,
-    dtype: str | Dtype | dict[str, str | Dtype] | None = ...,
+    dtype: str | Dtype | Mapping[str, str | Dtype] | None = ...,
     engine: Literal["xlrd", "openpyxl", "odf", "pyxlsb"] | None = ...,
-    converters: dict[int | str, Callable[[object], object]] | None = ...,
+    converters: Mapping[int | str, Callable[[object], object]] | None = ...,
     true_values: Iterable[Hashable] | None = ...,
     false_values: Iterable[Hashable] | None = ...,
     skiprows: int | Sequence[int] | Callable[[object], bool] | None = ...,
@@ -79,9 +80,9 @@ def read_excel(
     names: list[str] | None = ...,
     index_col: int | Sequence[int] | None = ...,
     usecols: Sequence[int] | Sequence[str] | Callable[[str], bool] | None = ...,
-    dtype: str | Dtype | dict[str, str | Dtype] | None = ...,
+    dtype: str | Dtype | Mapping[str, str | Dtype] | None = ...,
     engine: Literal["xlrd", "openpyxl", "odf", "pyxlsb"] | None = ...,
-    converters: dict[int | str, Callable[[object], object]] | None = ...,
+    converters: Mapping[int | str, Callable[[object], object]] | None = ...,
     true_values: Iterable[Hashable] | None = ...,
     false_values: Iterable[Hashable] | None = ...,
     skiprows: int | Sequence[int] | Callable[[object], bool] | None = ...,

tests/test_io.py

@@ -705,6 +705,15 @@ def test_read_excel_list():
         )
 
 
+def test_read_excel_dtypes():
+    # GH 440
+    df = pd.DataFrame({"a": [1, 2, 3], "b": ["x", "y", "z"], "c": [10.0, 20.0, 30.3]})
+    with ensure_clean(".xlsx") as path:
+        check(assert_type(df.to_excel(path), None), type(None))
+        dtypes = {"a": np.int64, "b": str, "c": np.float64}
+        check(assert_type(read_excel(path, dtype=dtypes), pd.DataFrame), pd.DataFrame)
+
+
 def test_excel_writer():
     with ensure_clean(".xlsx") as path:
         with pd.ExcelWriter(path) as ew: