Prevent ifelse() from being used to produce TRUE/FALSE or 1/0

Expressions like ifelse(x, TRUE, FALSE) and ifelse(x, FALSE, TRUE) are redundant; just x or !x suffice in R code where logical vectors are a core data structure. ifelse(x, 1, 0) is also as.numeric(x), but even this should be needed only rarely.

Usage

redundant_ifelse_linter(allow10 = FALSE)

Arguments

allow10

Logical, default FALSE. If TRUE, usage like ifelse(x, 1, 0) is allowed, i.e., only usage like ifelse(x, TRUE, FALSE) is linted.

See also

linters for a complete list of linters available in lintr.

Tags

best_practices, configurable, consistency, efficiency

Examples

# will produce lints
lint(
  text = "ifelse(x >= 2.5, TRUE, FALSE)",
  linters = redundant_ifelse_linter()
)
#> <text>:1:1: warning: [redundant_ifelse_linter] Just use the logical condition (or its negation) directly instead of calling ifelse(x, TRUE, FALSE)
#> ifelse(x >= 2.5, TRUE, FALSE)
#> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

lint(
  text = "ifelse(x < 2.5, 1L, 0L)",
  linters = redundant_ifelse_linter()
)
#> <text>:1:1: warning: [redundant_ifelse_linter] Prefer as.integer(x) to ifelse(x, 1L, 0L) if really needed.
#> ifelse(x < 2.5, 1L, 0L)
#> ^~~~~~~~~~~~~~~~~~~~~~~

# okay
lint(
  text = "x >= 2.5",
  linters = redundant_ifelse_linter()
)
#> ℹ No lints found.

# Note that this is just to show the strict equivalent of the example above;
# converting to integer is often unnecessary and the logical vector itself
# should suffice.
lint(
  text = "as.integer(x < 2.5)",
  linters = redundant_ifelse_linter()
)
#> ℹ No lints found.

lint(
  text = "ifelse(x < 2.5, 1L, 0L)",
  linters = redundant_ifelse_linter(allow10 = TRUE)
)
#> ℹ No lints found.