polars.Series.replace_strict

Series.replace_strict(
    old: IntoExpr | Sequence[Any] | Mapping[Any,
    Any],
    new: IntoExpr | Sequence[Any] | NoDefault = <no_default>,
    *,
    default: IntoExpr | NoDefault = <no_default>,
    return_dtype: PolarsDataType | None = None,
) → Self

Replace all values by different values.

Parameters:

old

Value or sequence of values to replace. Also accepts a mapping of values to their replacement as syntactic sugar for replace_strict(old=Series(mapping.keys()), new=Series(mapping.values())).

new

Value or sequence of values to replace by. Length must match the length of old or have length 1.

default

Set values that were not replaced to this value. If no default is specified, (default), an error is raised if any values were not replaced. Accepts expression input. Non-expression inputs are parsed as literals.

return_dtype

The data type of the resulting Series. If set to None (default), the data type is determined automatically based on the other inputs.

Raises:

InvalidOperationError

If any non-null values in the original column were not replaced, and no default was specified.

See also

replace

str.replace

Examples

Replace values by passing sequences to the old and new parameters.

>>> s = pl.Series([1, 2, 2, 3])
>>> s.replace_strict([1, 2, 3], [100, 200, 300])
shape: (4,)
Series: '' [i64]
[
    100
    200
    200
    300
]

Passing a mapping with replacements is also supported as syntactic sugar.

>>> mapping = {1: 100, 2: 200, 3: 300}
>>> s.replace_strict(mapping)
shape: (4,)
Series: '' [i64]
[
    100
    200
    200
    300
]

By default, an error is raised if any non-null values were not replaced. Specify a default to set all values that were not matched.

>>> mapping = {2: 200, 3: 300}
>>> s.replace_strict(mapping)  
Traceback (most recent call last):
...
polars.exceptions.InvalidOperationError: incomplete mapping specified for `replace_strict`
>>> s.replace_strict(mapping, default=-1)
shape: (4,)
Series: '' [i64]
[
    -1
    200
    200
    300
]

The default can be another Series.

>>> default = pl.Series([2.5, 5.0, 7.5, 10.0])
>>> s.replace_strict(2, 200, default=default)
shape: (4,)
Series: '' [f64]
[
    2.5
    200.0
    200.0
    10.0
]

Replacing by values of a different data type sets the return type based on a combination of the new data type and the default data type.

>>> s = pl.Series(["x", "y", "z"])
>>> mapping = {"x": 1, "y": 2, "z": 3}
>>> s.replace_strict(mapping)
shape: (3,)
Series: '' [i64]
[
    1
    2
    3
]
>>> s.replace_strict(mapping, default="x")
shape: (3,)
Series: '' [str]
[
    "1"
    "2"
    "3"
]

Set the return_dtype parameter to control the resulting data type directly.

>>> s.replace_strict(mapping, return_dtype=pl.UInt8)
shape: (3,)
Series: '' [u8]
[
    1
    2
    3
]