GH1226 Add Styler.map to the stubs

Author: loicdiridollou

pandas-stubs/io/formats/style.pyi

@@ -71,6 +71,9 @@ class Styler(StylerRenderer):
         formatter: ExtFormatter | None = ...,
     ) -> None: ...
     def concat(self, other: Styler) -> Styler: ...
+    def map(
+        self, func: Callable, subset: Subset | None = ..., **kwargs: Any
+    ) -> Styler: ...
     def set_tooltips(
         self,
         ttips: DataFrame,

tests/test_styler.py

@@ -30,7 +30,6 @@
 
 DF = DataFrame({"a": [1, 2, 3], "b": [3.14, 2.72, 1.61]})
 
-
 PWD = pathlib.Path(os.path.split(os.path.abspath(__file__))[0])
 
 if TYPE_CHECKING:
@@ -233,3 +232,12 @@ def test_styler_columns_and_index() -> None:
     styler = DF.style
     check(assert_type(styler.columns, Index), Index)
     check(assert_type(styler.index, Index), Index)
+
+
+def test_styler_map() -> None:
+    """Test type returned with Styler.map GH1226."""
+    df = DataFrame(data={"col1": [1, -2], "col2": [-3, 4]})
+    check(
+        assert_type(df.style.map(lambda v: "color: red;" if v < 0 else None), Styler),
+        Styler,
+    )