Update boxplot.py

Author: serhiisavingit

pandas/plotting/_matplotlib/boxplot.py

@@ -4,6 +4,8 @@
     TYPE_CHECKING,
     Literal,
     NamedTuple,
+    Optional,
+    Union,
 )
 import warnings
 
@@ -98,7 +100,8 @@ def __init__(self, data, return_type: str = "axes", **kwargs) -> None:
     # error: Signature of "_plot" incompatible with supertype "MPLPlot"
     @classmethod
     def _plot(  # type: ignore[override]
-        cls, ax: Axes, y: np.ndarray, column_num=None, return_type: str = "axes", **kwds
+        cls, ax: Axes, y: np.ndarray, column_num: Optional[int] = None, return_type: str = "axes", **kwds
+
     ):
         ys: np.ndarray | list[np.ndarray]
         if y.ndim == 2:
@@ -107,6 +110,9 @@ def _plot(  # type: ignore[override]
             #   if any cols are empty
             # GH 8181
             ys = [v if v.size > 0 else np.array([np.nan]) for v in ys]
+            for v in ys:
+                if v.size == 0:
+                    warnings.warn("Empty array detected, replacing with NaN", stacklevel=find_stack_level())
         else:
             ys = remove_na_arraylike(y)
         bp = ax.boxplot(ys, **kwds)
@@ -166,10 +172,7 @@ def _caps_c(self):
     def _get_colors(
         self,
         num_colors=None,
-        color_kwds: dict[str, MatplotlibColor]
-        | MatplotlibColor
-        | Collection[MatplotlibColor]
-        | None = "color",
+        color_kwds: Optional[Union[dict[str, MatplotlibColor], MatplotlibColor, Collection[MatplotlibColor]]] = "color",
     ) -> None:
         pass
 
@@ -391,8 +394,7 @@ def _get_colors():
                         result[key_to_index[key]] = value
                     else:
                         raise ValueError(
-                            f"color dict contains invalid key '{key}'. "
-                            f"The key must be either {valid_keys}"
+                            f"Invalid key '{key}' in color dictionary. Expected one of {valid_keys}. Please refer to documentation.")
                         )
             else:
                 result.fill(colors)