`polars filter` for lazyframe

Filter dataframe based in expression.

Signature

> polars filter {flags} (filter expression)

Parameters

filter expression: Expression that define the column selection.

Input/output types:

input	output
polars_dataframe	polars_dataframe
polars_lazyframe	polars_lazyframe
polars_expression	polars_expression

Examples

Filter dataframe using an expression

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

Filter dataframe for rows where dt is within the last 2 days of the maximum dt value

> [[dt val]; [2025-04-01 1] [2025-04-02 2] [2025-04-03 3] [2025-04-04 4]] | polars into-df | polars filter ((polars col dt) > ((polars col dt | polars max | $in - 2day)))
╭───┬────────────┬─────╮
│ # │     dt     │ val │
├───┼────────────┼─────┤
│ 0 │ a year ago │   3 │
│ 1 │ a year ago │   4 │
╰───┴────────────┴─────╯

Filter a single column in a group-by context

> [[a b]; [foo 1] [foo 2] [foo 3] [bar 2] [bar 3] [bar 4]] | polars into-df
                    | polars group-by a --maintain-order
                    | polars agg {
                        lt: (polars col b | polars filter ((polars col b) < 2) | polars sum)
                        gte: (polars col b | polars filter ((polars col b) >= 3) | polars sum)
                    }
                    | polars collect
╭───┬─────┬────┬─────╮
│ # │  a  │ lt │ gte │
├───┼─────┼────┼─────┤
│ 0 │ foo │  1 │   3 │
│ 1 │ bar │  0 │   7 │
╰───┴─────┴────┴─────╯

polars filter for lazyframe

Signature

Parameters

Input/output types:

Examples

`polars filter` for lazyframe