polars: GroupBy.agg()

code:py

def compute_age():

return date.today().year - pl.col("birthday").dt.year()

def avg_birthday(gender: str) -> pl.Expr:

return (

compute_age()

.filter(pl.col("gender") == gender)

.mean()

.alias(f"avg {gender} birthday")

)

q = (

dataset.lazy()

.group_by("state")

.agg(

avg_birthday("M"),

avg_birthday("F"),

(pl.col("gender") == "M").sum().alias("# male"),

(pl.col("gender") == "F").sum().alias("# female"),

)

.limit(5)

)

code:py

import polars as pl

df = pl.DataFrame(

{

}

)

grouped_df = df.group_by("group").agg(pl.col("values"))

grouped_df

code:result

shape: (2, 2)

┌───────┬───────────┐

│ group ┆ values │

│ --- ┆ --- │

╞═══════╪═══════════╡

└───────┴───────────┘