indAndSub function

Retrieve vector or array indices

ind2sub is just an alias for arrayInd. sub2ind is the reverse of ind2sub.

ind2sub(ind, .dim, .dimnames = NULL, useNames = FALSE)

sub2ind(sub, .dim)

Arguments

• ind: Vector indices.

• .dim: dim(.) integer vector

• .dimnames: optional list of character dimnames(.). If useNames is true, to be used for constructing dimnames for arrayInd() (and hence, which(*, arr.ind=TRUE)). If names(.dimnames) is not empty, these are used as column names. .dimnames[[1]] is used as row names.

• useNames: logical indicating if the value of arrayInd()

  should have (non-null) dimnames at all.

• sub: Array/matrix indices.

Returns

See arrayInd.

Examples

set.seed(12345)
mat <- matrix(round(runif(6, min = 0, max = 10)), nrow = 2, ncol = 3)
ind2sub(4, dim(mat))
sub2ind(c(2, 2), dim(mat))
subs <- as.matrix(expand.grid(1:2,2:3))
sub2ind(subs, dim(mat))