Skip to content

convert_units

laktory.narwhals_ext.expr.convert_units ¤

FUNCTION DESCRIPTION
convert_units

Units conversion

convert_units(self, input_unit, output_unit) ¤

Units conversion

PARAMETER DESCRIPTION
input_unit

Input units

TYPE: str

output_unit

Output units

TYPE: str

RETURNS DESCRIPTION
Expr

Output column

Examples:

import narwhals as nw
import polars as pl

import laktory as lk  # noqa: F401

df = nw.from_native(pl.DataFrame({"x": [1]}))
df = df.with_columns(
    y=nw.col("x").laktory.convert_units(input_unit="m", output_unit="ft")
)
print(df)
'''
┌──────────────────┐
|Narwhals DataFrame|
|------------------|
| | x | y       |  |
| |---|---------|  |
| | 1 | 3.28084 |  |
└──────────────────┘
'''
References

The units conversion function use planck convert as a backend.

Source code in laktory/narwhals_ext/expr/convert_units.py 
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
def convert_units(
    self,
    input_unit: str,
    output_unit: str,
) -> nw.Expr:
    """
    Units conversion

    Parameters
    ----------
    input_unit:
        Input units
    output_unit:
        Output units

    Returns
    -------
    :
        Output column

    Examples
    --------
    ```py
    import narwhals as nw
    import polars as pl

    import laktory as lk  # noqa: F401

    df = nw.from_native(pl.DataFrame({"x": [1]}))
    df = df.with_columns(
        y=nw.col("x").laktory.convert_units(input_unit="m", output_unit="ft")
    )
    print(df)
    '''
    ┌──────────────────┐
    |Narwhals DataFrame|
    |------------------|
    | | x | y       |  |
    | |---|---------|  |
    | | 1 | 3.28084 |  |
    └──────────────────┘
    '''
    ```

    References
    ----------
    The units conversion function use [planck](https://www.okube.ai/planck/) convert as a backend.
    """
    return units.convert(self._expr, input_unit, output_unit)