Method: Polars::Expr#agg_groups

Defined in:
lib/polars/expr.rb

#agg_groups ⇒ Expr

Get the group indexes of the group by operation.

Should be used in aggregation context only.

Examples:

df = Polars::DataFrame.new(
  {
    "group" => [
      "one",
      "one",
      "one",
      "two",
      "two",
      "two"
    ],
    "value" => [94, 95, 96, 97, 97, 99]
  }
)
df.group_by("group", maintain_order: true).agg(Polars.col("value").agg_groups)
# =>
# shape: (2, 2)
# ┌───────┬───────────┐
# │ group ┆ value     │
# │ ---   ┆ ---       │
# │ str   ┆ list[u32] │
# ╞═══════╪═══════════╡
# │ one   ┆ [0, 1, 2] │
# │ two   ┆ [3, 4, 5] │
# └───────┴───────────┘

Returns:



738
739
740
 
# File 'lib/polars/expr.rb', line 738

def agg_groups
  wrap_expr(_rbexpr.agg_groups)
end