DOC Clarify fill_value behavior in SimpleImputer
Fixes
@@ -176,9 +176,10 @@ class SimpleImputer(_BaseImputer):
strategy="constant" for fixed value imputation.
fill_value : str or numerical value, default=None
- When strategy == "constant", fill_value is used to replace all
- occurrences of missing_values.
- If left to the default, fill_value will be 0 when imputing numerical
+ When strategy == "constant", `fill_value` is used to replace all
+ occurrences of missing_values. For string or object data types,
+ `fill_value` must be a string.
+ If `None`, `fill_value` will be 0 when imputing numerical
data and "missing_value" for strings or object data types.
verbose : int, default=0
