`polars unnest` for dataframe

Decompose struct columns into separate columns for each of their fields. The new columns will be inserted into the dataframe at the location of the struct column.

This command requires a plugin

The polars unnest 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.

Command Type

plugin

Signature

> polars unnest {flags} ...rest

Flags

--separator, -s {string}: Optional separator to use when creating new column names.

Parameters

...rest: Columns to unnest.

Input/output types:

input	output
polars_dataframe	polars_dataframe
polars_lazyframe	polars_lazyframe

Examples

Unnest a dataframe

> [[id person]; [1 {name: "Bob", age: 36}] [2 {name: "Betty", age: 63}]]
                    | polars into-df -s {id: i64, person: {name: str, age: u8}}
                    | polars unnest person
                    | polars get id name age
                    | polars sort-by id
╭───┬────┬───────┬─────╮
│ # │ id │ name  │ age │
├───┼────┼───────┼─────┤
│ 0 │  1 │ Bob   │  36 │
│ 1 │  2 │ Betty │  63 │
╰───┴────┴───────┴─────╯

Unnest a lazy dataframe

> [[id person]; [1 {name: "Bob", age: 36}] [2 {name: "Betty", age: 63}]]
                    | polars into-df -s {id: i64, person: {name: str, age: u8}}
                    | polars into-lazy
                    | polars unnest person
                    | polars select (polars col id) (polars col name) (polars col age)
                    | polars collect
                    | polars sort-by id
╭───┬────┬───────┬─────╮
│ # │ id │ name  │ age │
├───┼────┼───────┼─────┤
│ 0 │  1 │ Bob   │  36 │
│ 1 │  2 │ Betty │  63 │
╰───┴────┴───────┴─────╯

Unnest with a custom separator

> [[id person]; [1 {name: "Bob", age: 36}] [2 {name: "Betty", age: 63}]]
                    | polars into-df -s {id: i64, person: {name: str, age: u8}}
                    | polars unnest person -s "_"
                    | polars get id person_name person_age
                    | polars sort-by id
╭───┬────┬─────────────┬────────────╮
│ # │ id │ person_name │ person_age │
├───┼────┼─────────────┼────────────┤
│ 0 │  1 │ Bob         │         36 │
│ 1 │  2 │ Betty       │         63 │
╰───┴────┴─────────────┴────────────╯