polars.Expr.map_dict#

Expr.map_dict( mapping: dict[Any, Any], *, default: Any = None, return_dtype: PolarsDataType | None = None, ) → Self[source]#

Replace values in column according to remapping dictionary.

Deprecated since version 0.19.16: This method has been renamed to replace(). The default behavior has changed to keep any values not present in the mapping unchanged. Pass default=None to keep existing behavior.

Parameters:

mapping: Dictionary containing the before/after values to map.
default: Value to use when the remapping dict does not contain the lookup value. Accepts expression input. Non-expression inputs are parsed as literals. Use pl.first(), to keep the original value.
return_dtype: Set return dtype to override automatic return dtype determination.