R: Get the index of the first/last TRUE

wf {checkmate} | R Documentation

## Get the index of the first/last TRUE

### Description

A quick C implementation for “which.first” (`head(which(x), 1)`) and “which.last” (`tail(which(x), 1)`).

### Usage

    wf(x, use.names = TRUE)

    wl(x, use.names = TRUE)

### Arguments

`x` | [`logical`] Logical vector.
`use.names` | [`logical(1)`] If `TRUE` and `x` is named, the result is also named.

### Value

[`integer(1)` | `integer(0)`]. Returns the index of the first/last `TRUE` value in `x` or an empty integer vector if none is found. NAs are ignored.

### Examples

    wf(c(FALSE, TRUE))
    wl(c(FALSE, FALSE))
    wf(NA)

[Package checkmate version 1.8.2 Index]