##' Find the raw indices for given indices in array form.
##'
##' This is exactly the inverse function of `arrayInd()'.
##' @title Raw indices finder for array.
##' @param arr.ind "matrix or vector"
##' When it is a matrix, the length of columns should be the as the
##' length of the "dims". When it is a vector, the argument length should be
##' the same as the length of "dims".
##' @param dims "vector"
##' The dimension of the array. Note that the last dimension is not
##' needed in the calculations, so if you may just write "NA" there.
##' @return "vector" The raw indices.
##' @author Feng Li, Department of Statistics, Stockholm University, Sweden.
##' @note Created: Wed Mar 14 18:03:01 CET 2012;
##' Current: Wed Mar 14 18:03:09 CET 2012.
##' @export
whichInd <- function(arr.ind, dims)
{
arr.indMat <- matrix(arr.ind, ncol = length(dims))
idx1 <- cumprod(dims[-length(dims)])
idx2 <- arr.indMat[, -1, drop = FALSE]-1
out <- rowSums(idx1*idx2) + arr.indMat[, 1]
return(out)
}
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