polars.cum_count#

polars.cum_count(*columns: str, reverse: bool = False) → Expr[source]#

Return the cumulative count of the non-null values in the column.

This function is syntactic sugar for col(columns).cum_count().

If no arguments are passed, returns the cumulative count of a context. Rows containing null values count towards the result.

Parameters:

*columns: Name(s) of the columns to use.
reverse: Reverse the operation.

Examples

>>> df = pl.DataFrame({"a": [1, 2, None], "b": [3, None, None]})
>>> df.select(pl.cum_count("a"))
shape: (3, 1)
┌─────┐
│ a   │
│ --- │
│ u32 │
╞═════╡
│ 1   │
│ 2   │
│ 2   │
└─────┘