keep_at: Keep/discard elements based on their name/position

In purrr: Functional Programming Tools

Keep/discard elements based on their name/position

Description

keep_at() and discard_at() are similar to [ or dplyr::select(): they return the same type of data structure as the input, but only containing the requested elements. (If you're looking for a function similar to [[ see pluck()/chuck()).

Usage

keep_at(x, at)

discard_at(x, at)

Arguments

x	A list or atomic vector.
at	A logical, integer, or character vector giving the elements to select. Alternatively, a function that takes a vector of names, and returns a logical, integer, or character vector of elements to select. : if the tidyselect package is installed, you can use vars() and tidyselect helpers to select elements.

See Also

keep()/discard() to keep/discard elements by value.

Examples

x <- c(a = 1, b = 2, cat = 10, dog = 15, elephant = 5, e = 10)
x |> keep_at(letters)
x |> discard_at(letters)

# Can also use a function
x |> keep_at(\(x) nchar(x) == 3)
x |> discard_at(\(x) nchar(x) == 3)

purrr documentation built on Nov. 5, 2025, 7:27 p.m.