Function col

col(col): pl.Expr

A column in a DataFrame. Can be used to select:

a single column by name
all columns by using a wildcard "*"
column by regular expression if the regex starts with ^ and ends with $

Parameters

col:
    | string
    | DataType
    | string[]
    | pl.Series<any, string>

Returns pl.Expr

Example

> df = pl.DataFrame({
> "ham": [1, 2, 3],
> "hamburger": [11, 22, 33],
> "foo": [3, 2, 1]})
> df.select(col("foo"))
shape: (3, 1)
╭─────╮
│ foo │
│ --- │
│ i64 │
╞═════╡
│ 3   │
├╌╌╌╌╌┤
│ 2   │
├╌╌╌╌╌┤
│ 1   │
╰─────╯
> df.select(col("*"))
shape: (3, 3)
╭─────┬───────────┬─────╮
│ ham ┆ hamburger ┆ foo │
│ --- ┆ ---       ┆ --- │
│ i64 ┆ i64       ┆ i64 │
╞═════╪═══════════╪═════╡
│ 1   ┆ 11        ┆ 3   │
├╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 2   ┆ 22        ┆ 2   │
├╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 3   ┆ 33        ┆ 1   │
╰─────┴───────────┴─────╯
> df.select(col("^ham.*$"))
shape: (3, 2)
╭─────┬───────────╮
│ ham ┆ hamburger │
│ --- ┆ ---       │
│ i64 ┆ i64       │
╞═════╪═══════════╡
│ 1   ┆ 11        │
├╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2   ┆ 22        │
├╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 3   ┆ 33        │
╰─────┴───────────╯
> df.select(col("*").exclude("ham"))
shape: (3, 2)
╭───────────┬─────╮
│ hamburger ┆ foo │
│ ---       ┆ --- │
│ i64       ┆ i64 │
╞═══════════╪═════╡
│ 11        ┆ 3   │
├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 22        ┆ 2   │
├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 33        ┆ 1   │
╰───────────┴─────╯
> df.select(col(["hamburger", "foo"])
shape: (3, 2)
╭───────────┬─────╮
│ hamburger ┆ foo │
│ ---       ┆ --- │
│ i64       ┆ i64 │
╞═══════════╪═════╡
│ 11        ┆ 3   │
├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 22        ┆ 2   │
├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 33        ┆ 1   │
╰───────────┴─────╯
> df.select(col(pl.Series(["hamburger", "foo"]))
shape: (3, 2)
╭───────────┬─────╮
│ hamburger ┆ foo │
│ ---       ┆ --- │
│ i64       ┆ i64 │
╞═══════════╪═════╡
│ 11        ┆ 3   │
├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 22        ┆ 2   │
├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌┤
│ 33        ┆ 1   │
╰───────────┴─────╯

Function col

Parameters

Returns pl.Expr

Example

Settings