[R] Inverse function to 'which'?
Henrik Bengtsson
henrikb at braju.com
Fri Jul 6 20:44:18 CEST 2001
Is there an inverse function to 'which' available, which creates a logical
vector/matrix from indices? I wrote my own, but if there is a standard
function I would like to use that instead. Example:
x <- c(TRUE, TRUE, FALSE, TRUE, FALSE, FALSE)
unwhich(which(x)) # [1] TRUE TRUE FALSE TRUE
unwhich(which(x), length(x)) # [1] TRUE TRUE FALSE TRUE FALSE FALSE
y <- matrix(x, nrow=3, ncol=2)
unwhich(which(y, arr.ind=TRUE)) # "Minimum" size
unwhich(which(y, arr.ind=TRUE), dim(y)) # Same dimensions as y
Thanks
Henrik Bengtsson
h e n r i k b @ b r a j u . c o m
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