unnecessary_concatenation_linter {lintr}

Unneeded concatenation linter

Description

Check that the c() function is not used without arguments nor with a single constant.

Usage

unnecessary_concatenation_linter(allow_single_expression = TRUE)

Arguments

allow_single_expression

Logical, default TRUE. If FALSE, one-expression usages of c() are always linted, e.g. c(x) and c(matrix(...)). In some such cases, c() is being used for its side-effect of stripping non-name attributes; it is usually preferable to use the more readable as.vector() instead. as.vector() is not always preferable, for example with environments (especially, R6 objects), in which case list() is the better alternative.

Tags

configurable, efficiency, readability, style

See Also

linters for a complete list of linters available in lintr.

Examples

# will produce lints
lint(
  text = "x <- c()",
  linters = unnecessary_concatenation_linter()
)

lint(
  text = "x <- c(TRUE)",
  linters = unnecessary_concatenation_linter()
)

lint(
  text = "x <- c(1.5 + 2.5)",
  linters = unnecessary_concatenation_linter(allow_single_expression = FALSE)
)

# okay
lint(
  text = "x <- NULL",
  linters = unnecessary_concatenation_linter()
)

# In case the intent here was to seed a vector of known size
lint(
  text = "x <- integer(4L)",
  linters = unnecessary_concatenation_linter()
)

lint(
  text = "x <- TRUE",
  linters = unnecessary_concatenation_linter()
)

lint(
  text = "x <- c(1.5 + 2.5)",
  linters = unnecessary_concatenation_linter(allow_single_expression = TRUE)
)