polars.Expr.cum_prod#
- Expr.cum_prod(*, reverse: bool = False) Expr [source]#
Get an array with the cumulative product computed at every element.
- Parameters:
- reverse
Reverse the operation.
Notes
Dtypes in {Int8, UInt8, Int16, UInt16} are cast to Int64 before summing to prevent overflow issues.
Examples
>>> df = pl.DataFrame({"a": [1, 2, 3, 4]}) >>> df.with_columns( ... pl.col("a").cum_prod().alias("cum_prod"), ... pl.col("a").cum_prod(reverse=True).alias("cum_prod_reverse"), ... ) shape: (4, 3) ┌─────┬──────────┬──────────────────┐ │ a ┆ cum_prod ┆ cum_prod_reverse │ │ --- ┆ --- ┆ --- │ │ i64 ┆ i64 ┆ i64 │ ╞═════╪══════════╪══════════════════╡ │ 1 ┆ 1 ┆ 24 │ │ 2 ┆ 2 ┆ 24 │ │ 3 ┆ 6 ┆ 12 │ │ 4 ┆ 24 ┆ 4 │ └─────┴──────────┴──────────────────┘