polars cast for dataframe

Cast a column to a different dtype.

This command requires a plugin

The polars cast command resides in the polars plugin. To use this command, you must install and register nu_plugin_polars. See the Plugins chapter in the book for more information.

Signature

> polars cast {flags} (dtype) (column)

Parameters

  • dtype: The dtype to cast the column to
  • column: The column to cast. Required when used with a dataframe.

Input/output types:

inputoutput
anyany

Examples

Cast a column in a dataframe to a different dtype

> [[a b]; [1 2] [3 4]] | polars into-df | polars cast u8 a | polars schema
╭───┬─────╮
│ a │ u8  │
│ b │ i64 │
╰───┴─────╯

Cast a column in a lazy dataframe to a different dtype

> [[a b]; [1 2] [3 4]] | polars into-df | polars into-lazy | polars cast u8 a | polars schema
╭───┬─────╮
│ a │ u8  │
│ b │ i64 │
╰───┴─────╯

Cast a column in a expression to a different dtype

> [[a b]; [1 2] [1 4]] | polars into-df | polars group-by a | polars agg [ (polars col b | polars cast u8 | polars min | polars as "b_min") ] | polars schema