Skip to content

Count how often a value occurs in every sub-array

Description

Count how often a value occurs in every sub-array

Usage

<Expr>$arr$count_matches(element)

Arguments

element An Expr or something coercible to an Expr that produces a single value.

Value

A polars expression

Examples

library("polars")

df <- pl$DataFrame(
  values = list(c(1, 2), c(1, 1), c(2, 2))
)$cast(pl$Array(pl$Int64, 2))
df$with_columns(number_of_twos = pl$col("values")$arr$count_matches(2))

#> shape: (3, 2)
#> ┌───────────────┬────────────────┐
#> │ values        ┆ number_of_twos │
#> │ ---           ┆ ---            │
#> │ array[i64, 2] ┆ u32            │
#> ╞═══════════════╪════════════════╡
#> │ [1, 2]        ┆ 1              │
#> │ [1, 1]        ┆ 0              │
#> │ [2, 2]        ┆ 2              │
#> └───────────────┴────────────────┘