Block usage of ==, != on logical vectors

Testing x == TRUE is redundant if x is a logical vector. Wherever this is used to improve readability, the solution should instead be to improve the naming of the object to better indicate that its contents are logical. This can be done using prefixes (is, has, can, etc.). For example, is_child, has_parent_supervision, can_watch_horror_movie clarify their logical nature, while child, parent_supervision, watch_horror_movie don't.

Usage

redundant_equals_linter()

See also

• linters for a complete list of linters available in lintr.

• outer_negation_linter()

Tags

best_practices, common_mistakes, efficiency, readability

Examples

# will produce lints
lint(
  text = "if (any(x == TRUE)) 1",
  linters = redundant_equals_linter()
)
#> <text>:1:9: warning: [redundant_equals_linter] Using == on a logical vector is redundant. Well-named logical vectors can be used directly in filtering. For data.table's `i` argument, wrap the column name in (), like `DT[(is_treatment)]`.
#> if (any(x == TRUE)) 1
#>         ^~~~~~~~~

lint(
  text = "if (any(x != FALSE)) 0",
  linters = redundant_equals_linter()
)
#> <text>:1:9: warning: [redundant_equals_linter] Using != on a logical vector is redundant. Well-named logical vectors can be used directly in filtering. For data.table's `i` argument, wrap the column name in (), like `DT[(is_treatment)]`.
#> if (any(x != FALSE)) 0
#>         ^~~~~~~~~~

lint(
  text = "dt[is_tall == FALSE, y]",
  linters = redundant_equals_linter()
)
#> <text>:1:4: warning: [redundant_equals_linter] Using == on a logical vector is redundant. Well-named logical vectors can be used directly in filtering. For data.table's `i` argument, wrap the column name in (), like `DT[(is_treatment)]`.
#> dt[is_tall == FALSE, y]
#>    ^~~~~~~~~~~~~~~~

# okay
lint(
  text = "if (any(x)) 1",
  linters = redundant_equals_linter()
)
#> ℹ No lints found.

lint(
  text = "if (!all(x)) 0",
  linters = redundant_equals_linter()
)
#> ℹ No lints found.

# in `{data.table}` semantics, `dt[x]` is a join, `dt[(x)]` is a subset
lint(
  text = "dt[(!is_tall), y]",
  linters = redundant_equals_linter()
)
#> ℹ No lints found.