R: Inverse Which

Unwhich {DescTools} | R Documentation

## Inverse Which

### Description

The inverse function to `which` creates a logical vector/matrix from indices.

### Usage

    Unwhich(idx, n, useNames = TRUE)

### Arguments

`idx` | the indices as returned by `which`.
`n` | integer, the length of the original vector.
`useNames` | logical, determining if the names of the indices should be preserved.

### Value

a logical vector of the length n, with `TRUE` on the positions `i`.

### Author(s)

Nick Sabbe

### References

http://stackoverflow.com/questions/7659833/inverse-of-which

### See Also

`which`

### Examples

    ll <- c(TRUE, FALSE, TRUE, NA, FALSE, FALSE, TRUE)
    names(ll) <- letters[seq(ll)]
    i <- which(ll)
    # back again (loosing the names of the FALSEs)
    Unwhich(i, length(ll))

[Package DescTools version 0.99.25 Index]