Find head/tail that all satisfies a predicate.

head_while(.x, .p, ...)

tail_while(.x, .p, ...)

Arguments

.x	A list or atomic vector.
.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.
...	Additional arguments passed on to the mapped function.

Value

A vector the same type as .x.

Examples

pos <- function(x) x >= 0
head_while(5:-5, pos)
#> [1] 5 4 3 2 1 0
tail_while(5:-5, negate(pos))
#> [1] -1 -2 -3 -4 -5

big <- function(x) x > 100
head_while(0:10, big)
#> integer(0)
tail_while(0:10, big)
#> integer(0)