Apply every value with an R fun

Description

About as slow as regular non-vectorized R. Similar to using R sapply on a vector.

<Series>$map_elements(
  fun,
  datatype = NULL,
  strict_return_type = TRUE,
  allow_fail_eval = FALSE
)

`fun`	r function, should take a single value as input and return one.
`datatype`	DataType of return value. Default NULL means same as input.
`strict_return_type`	bool, default TRUE: fail on wrong return type, FALSE: convert to polars Null
`allow_fail_eval`	bool, default FALSE: raise R fun error, TRUE: convert to polars Null

Series

library(polars)

s = as_polars_series(letters[1:5], "ltrs")
f = \(x) paste(x, ":", as.integer(charToRaw(x)))
s$map_elements(f, pl$String)

#> polars Series: shape: (5,)
#> Series: 'ltrs_apply' [str]
#> [
#>  "a : 97"
#>  "b : 98"
#>  "c : 99"
#>  "d : 100"
#>  "e : 101"
#> ]

# same as
as_polars_series(sapply(s$to_r(), f), s$name)

#> polars Series: shape: (5,)
#> Series: 'ltrs' [str]
#> [
#>  "a : 97"
#>  "b : 98"
#>  "c : 99"
#>  "d : 100"
#>  "e : 101"
#> ]