polars select for lazyframe

Selects columns from lazyframe.

This command requires a plugin

The polars select 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 select {flags} ...rest

Parameters

  • ...rest: Expression(s) that define the column selection

Input/output types:

inputoutput
anyany

Examples

Select a column from the dataframe

> [[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a
╭───┬───╮
│ # │ a │
├───┼───┤
│ 0 │ 6 │
│ 1 │ 4 │
│ 2 │ 2 │
╰───┴───╯

Select a column from a dataframe using a record

> [[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select {c: ((polars col a) * 2)}
╭───┬────╮
│ # │ c  │
├───┼────┤
│ 0 │ 12 │
│ 1 │  8 │
│ 2 │  4 │
╰───┴────╯

Select a column from a dataframe using a mix of expressions and record of expressions

> [[a b]; [6 2] [4 2] [2 2]] | polars into-df | polars select a b {c: ((polars col a) ** 2)}
╭───┬───┬───┬────╮
│ # │ a │ b │ c  │
├───┼───┼───┼────┤
│ 0 │ 6 │ 2 │ 36 │
│ 1 │ 4 │ 2 │ 16 │
│ 2 │ 2 │ 2 │  4 │
╰───┴───┴───┴────╯