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Negate a predicate function so it selects what it previously rejected

Source: R/adverb-negate.R
negate.Rd

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

Usage

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). You must use .x to refer to the first argument). Only recommended if you require backward compatibility with older versions of R.

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  TRUE  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE  TRUE
#> 
#> $z
#>  [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q"
#> [18] "r" "s" "t" "u" "v" "w" "x" "y" "z"
#>