Laktory Extension

Narwhals provides a rich set of DataFrame methods and expressions that work seamlessly across supported backends such as Spark and Polars. Laktory builds on top of Narwhals and introduces additional methods and functions under the laktory namespace.

DataFrame

The DataFrame extension adds a laktory namespace to Narwhals DataFrame and LazyFrame objects. For example, you can use the with_row_index method:

import narwhals as nw
import polars as pl

import laktory as lk  # noqa: F401

df0 = nw.from_native(
    pl.DataFrame(
        {
            "x": [0, 0, 0, 1, 1, 1],
            "y": [3, 2, 1, 1, 2, 3],
            "z": [0, 1, 3, 9, 16, 25],
        }
    )
)

df = df0.laktory.with_row_index(name="idx", order_by=["y"], partition_by="x")

Expr

The expression extension adds a laktory namespace to Narwhals Expr objects. For example, you can use the current_timestamp method:

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")
)

Functions

The functions extension adds a laktory namespace to the Narwhals module. For example, you can use the current_timestamp function:

import narwhals as nw
import polars as pl

import laktory as lk  # noqa: F401

df = nw.from_native(pl.DataFrame({"x": [0, 1]}))
df = df.with_columns(tstamp=nw.laktory.current_timestamp())

You can also create your own custom extension