polars first
For dataframe.
Show only the first number of rows or create a first expression
warning This command requires a plugin The
polars firstcommand resides in thepolarsplugin. To use this command, you must install and registernu_plugin_polars. See the Plugins chapter in the book for more information.
Command Type
plugin
Signature
> polars first {flags} (rows)
Parameters
rows: Starting from the front, the number of rows to return.
Input/output types:
| input | output |
|---|---|
| polars_expression | polars_expression |
| polars_selector | polars_expression |
| polars_dataframe | polars_dataframe |
| polars_lazyframe | polars_lazyframe |
| polars_group_by | polars_lazyframe |
Examples
Return the first row of a dataframe
> [[a b]; [1 2] [3 4]] | polars into-df | polars first
╭───┬───┬───╮
│ # │ a │ b │
├───┼───┼───┤
│ 0 │ 1 │ 2 │
╰───┴───┴───╯
Return the first two rows of a dataframe
> [[a b]; [1 2] [3 4]] | polars into-df | polars first 2
╭───┬───┬───╮
│ # │ a │ b │
├───┼───┼───┤
│ 0 │ 1 │ 2 │
│ 1 │ 3 │ 4 │
╰───┴───┴───╯
Creates a first expression from a column
> polars col a | polars first
Aggregate the first values in the group.
> [[a b c d]; [1 0.5 true Apple] [2 0.5 true Orange] [2 4 true Apple] [3 10 false Apple] [4 13 false Banana] [5 14 true Banana]] | polars into-df -s {a: u8, b: f32, c: bool, d: str} | polars group-by d | polars first | polars sort-by [a] | polars collect
╭───┬────────┬───┬───────┬───────╮
│ # │ d │ a │ b │ c │
├───┼────────┼───┼───────┼───────┤
│ 0 │ Apple │ 1 │ 0.50 │ true │
│ 1 │ Orange │ 2 │ 0.50 │ true │
│ 2 │ Banana │ 4 │ 13.00 │ false │
╰───┴────────┴───┴───────┴───────╯
Ported from nushell/nushell.github.io. Copyright (c) 2021 Nushell Project. MIT License.