Skip to contents

Block usage of comparison operators with known-list() functions like lapply

Source: R/list_comparison_linter.R
list_comparison_linter.Rd

Usage like lapply(x, sum) > 10 is awkward because the list must first be coerced to a vector for comparison. A function like vapply() should be preferred.

Usage

list_comparison_linter()

See also

linters for a complete list of linters available in lintr.

Tags

best_practices, common_mistakes

Examples

# will produce lints
lint(
  text = "lapply(x, sum) > 10",
  linters = list_comparison_linter()
)
#> <text>:1:1: warning: [list_comparison_linter] The output of lapply(), a list(), is being coerced for comparison by `>`. Instead, use a mapper that generates a vector with the correct type directly, for example vapply(x, FUN, character(1L)) if the output is a string.
#> lapply(x, sum) > 10
#> ^~~~~~~~~~~~~~~~~~~

# okay
lint(
  text = "unlist(lapply(x, sum)) > 10",
  linters = list_comparison_linter()
)
#> ℹ No lints found.