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Unwhich: Inverse Which

Description

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

Usage

Unwhich(idx, n = max(idx), useNames = TRUE)

Value

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

Arguments

idx

the indices as returned by which.

n

integer, the length of the original vector. This must not be less than max(idx), which is also the default.

useNames

logical, determining if the names of the indices should be preserved.

Author

Nick Sabbe

References

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

See Also

Examples

Run this code
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))

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