Aggregation

Expr.agg_groups()	Get the group indexes of the group by operation.
Expr.all(*[, ignore_nulls])	Return whether all values in the column are True.
Expr.any(*[, ignore_nulls])	Return whether any of the values in the column are True.
Expr.approx_n_unique()	Approximate count of unique values.
Expr.arg_max()	Get the index of the maximal value.
Expr.arg_min()	Get the index of the minimal value.
Expr.bitwise_and()	Perform an aggregation of bitwise ANDs.
Expr.bitwise_or()	Perform an aggregation of bitwise ORs.
Expr.bitwise_xor()	Perform an aggregation of bitwise XORs.
Expr.count()	Return the number of non-null elements in the column.
Expr.first(*[, ignore_nulls])	Get the first value.
Expr.implode()	Aggregate values into a list.
Expr.last(*[, ignore_nulls])	Get the last value.
Expr.len()	Return the number of elements in the column.
Expr.max()	Get maximum value.
Expr.max_by(by)	Get maximum value, ordered by another expression.
Expr.mean()	Get mean value.
Expr.median()	Get median value using linear interpolation.
Expr.min()	Get minimum value.
Expr.min_by(by)	Get minimum value, ordered by another expression.
Expr.n_unique()	Count unique values.
Expr.nan_max()	Get maximum value, but propagate/poison encountered NaN values.
Expr.nan_min()	Get minimum value, but propagate/poison encountered NaN values.
Expr.null_count()	Count null values.
Expr.product()	Compute the product of an expression.
Expr.quantile(quantile[, interpolation])	Get quantile value.
Expr.std([ddof])	Get standard deviation.
Expr.sum()	Get sum value.
Expr.var([ddof])	Get variance.