Negate a predicate function.

negate(.p)

Arguments

.p	A single predicate function, a formula describing such a predicate function, or a logical vector of the same length as `.x`. Alternatively, if the elements of `.x` are themselves lists of objects, a string indicating the name of a logical element in the inner lists. Only those elements where `.p` evaluates to `TRUE` will be modified.

Value

A new predicate function.

Examples

negate("x")
#> <composed>
#> 1. function (x, ...) 
#> pluck(x, "x", .default = NULL)
#> <environment: 0x7f96419f3430>
#> 
#> 2. function (.x) 
#> !.x
#> <bytecode: 0x7f9641919dd0>
#> <environment: 0x7f96419df468>
negate(is.null)
#> <composed>
#> 1. function (x) 
#> .Primitive("is.null")(x)
#> 
#> 2. function (.x) 
#> !.x
#> <bytecode: 0x7f9641919dd0>
#> <environment: 0x7f964034d4f8>
negate(~ .x > 0)
#> <composed>
#> 1. <lambda>
#> function (..., .x = ..1, .y = ..2, . = ..1) 
#> .x > 0
#> <environment: 0x7f9641ac3cf0>
#> attr(,"class")
#> [1] "rlang_lambda_function" "function"             
#> 
#> 2. function (.x) 
#> !.x
#> <bytecode: 0x7f9641919dd0>
#> <environment: 0x7f963eddff38>

x <- transpose(list(x = 1:10, y = rbernoulli(10)))
x %>% keep("y") %>% length()
#> [1] 7
x %>% keep(negate("y")) %>% length()
#> [1] 3
# Same as
x %>% discard("y") %>% length()
#> [1] 3