In tidyverse/tidyselect: Select from a Set of Strings

Functions like starts_with(), contains() or matches() are selection helpers that only work in a selection context, e.g. dplyr::select() or the cols argument of tidyr::pivot_longer().

Using a selection helper anywhere else results in an error:

starts_with("foo")

mtcars[contains("foo")]

subset(mtcars, select = matches("foo"))

If you see this error, you may have used a selection helper in the wrong place, possibly as the result of a typo (e.g. misplaced comma or wrong argument name). Alternatively, you may be deliberately trying to reduce duplication in your code by extracting out a selection into a variable:

my_vars <- c(name, species, ends_with("color"))

To make this work you'll need to do two things:

• Wrap the whole thing in a function
• Use any_of() or all_of() instead of bare variable names

my_vars <- function() {
  c(any_of(c("name", "species")), ends_with("color"))
}
dplyr::select(starwars, my_vars())

tidyverse/tidyselect documentation built on March 14, 2024, 3:16 p.m.