LazyGroupBy

The LazyGroupBy class represents a grouped lazy computation. It is created by calling LazyFrame::groupBy() and provides methods to aggregate grouped data.

Methods

agg

Apply custom aggregation expressions.

param array $expressions:

Array of Polars\Expr objects

returns:

LazyFrame

Example:

$result = $df->lazy()
    ->groupBy([Expr::col('group')])
    ->agg([
        Expr::col('value')->sum(),
        Expr::col('score')->mean(),
    ])
    ->collect();

count

Count rows per group.

first

Get the first row per group.

last

Get the last row per group.

head

Get the first n rows per group.

tail

Get the last n rows per group.

sum

Sum all numeric columns per group.

mean

Mean of all numeric columns per group.

median

Median of all numeric columns per group.

min

Minimum of all columns per group.

max

Maximum of all columns per group.