Return the cumulative max computed at every element.
Description
Return the cumulative max computed at every element.
Usage
<Expr>$cum_max(..., reverse = FALSE)
Arguments
…
|
These dots are for future extensions and must be empty. |
reverse
|
If TRUE, start from the last value.
|
Details
The Dtypes Int8, UInt8, Int16 and UInt16 are cast to Int64 before summing to prevent overflow issues.
Value
A polars expression
Examples
library("polars")
pl$DataFrame(a = c(1:4, 2L))$with_columns(
cum_max = pl$col("a")$cum_max(),
cum_max_reversed = pl$col("a")$cum_max(reverse = TRUE)
)
#> shape: (5, 3)
#> ┌─────┬─────────┬──────────────────┐
#> │ a ┆ cum_max ┆ cum_max_reversed │
#> │ --- ┆ --- ┆ --- │
#> │ i32 ┆ i32 ┆ i32 │
#> ╞═════╪═════════╪══════════════════╡
#> │ 1 ┆ 1 ┆ 4 │
#> │ 2 ┆ 2 ┆ 4 │
#> │ 3 ┆ 3 ┆ 4 │
#> │ 4 ┆ 4 ┆ 4 │
#> │ 2 ┆ 4 ┆ 2 │
#> └─────┴─────────┴──────────────────┘