Negate a predicate function so it selects what it previously rejected

Negating a function changes TRUE to FALSE and FALSE to TRUE.

negate(.p)

Arguments

.p

A predicate function (i.e. a function that returns either TRUE or FALSE) specified in one of the following ways:

• A named function, e.g. is.character.

• An anonymous function, e.g. \(x) all(x < 0) or function(x) all(x < 0).

• A formula, e.g. ~ all(.x < 0). Use .x to refer to the first argument. No longer recommended.

Value

A new predicate function.

Adverbs

This function is called an adverb because it modifies the effect of a function (a verb). If you'd like to include a function created an adverb in a package, be sure to read faq-adverbs-export.

See also

Other adverbs: auto_browse(), compose(), insistently(), partial(), possibly(), quietly(), safely(), slowly()

Examples

x <- list(x = 1:10, y = rbernoulli(10), z = letters)
x |> keep(is.numeric) |> names()
#> [1] "x"
x |> keep(negate(is.numeric)) |> names()
#> [1] "y" "z"
# Same as
x |> discard(is.numeric)
#> $y
#>  [1]  TRUE FALSE FALSE  TRUE  TRUE FALSE FALSE  TRUE FALSE FALSE
#> 
#> $z
#>  [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s"
#> [20] "t" "u" "v" "w" "x" "y" "z"
#>