polars.cum_sum_horizontal#

polars.cum_sum_horizontal(*exprs: IntoExpr | Iterable[IntoExpr]) → Expr[source]#

Cumulatively sum all values horizontally across columns.

Parameters:

*exprs: Column(s) to use in the aggregation. Accepts expression input. Strings are parsed as column names, other non-expression inputs are parsed as literals.

Examples

>>> df = pl.DataFrame(
...     {
...         "a": [1, 8, 3],
...         "b": [4, 5, None],
...         "c": ["x", "y", "z"],
...     }
... )
>>> df.with_columns(pl.cum_sum_horizontal("a", "b"))
shape: (3, 4)
┌─────┬──────┬─────┬───────────┐
│ a   ┆ b    ┆ c   ┆ cum_sum   │
│ --- ┆ ---  ┆ --- ┆ ---       │
│ i64 ┆ i64  ┆ str ┆ struct[2] │
╞═════╪══════╪═════╪═══════════╡
│ 1   ┆ 4    ┆ x   ┆ {1,5}     │
│ 8   ┆ 5    ┆ y   ┆ {8,13}    │
│ 3   ┆ null ┆ z   ┆ {3,null}  │
└─────┴──────┴─────┴───────────┘