collapse_mode: Collapse multiple modes into one mode.
In tensr: Covariance Inference and Decompositions for Tensor Datasets

Description Usage Arguments Details Value Author(s) Examples

Given an array X and a vector of integers m, collapse_mode returns an array of lower order where the first mode indexes the modes indicated in m.

1	collapse_mode(X, m)

`X`	An array whose modes we are collapsing.
`m`	A vector of integers giving the modes to collapse.

Transforms an array into another array where the provided modes are collapsed into one mode. The indexing along this new mode is in lexicographical order of the indices of the collapsed modes. The collapsed mode is the first mode unless length(m) == 1, then collapse_mode simply returns X.

If X is of order K and length(m) = q, then returns an array Y of order K - q + 1, where the modes indicated in m are combined to be the first mode in Y.

David Gerard.

X <- array(rep(c(1, 2), 8), dim = c(2, 2, 2, 2))
X
#mode 1 is now mode 2, modes 2, 3, and 4 are combined to be mode 1.
collapse_mode(X, c(2, 3, 4))
collapse_mode(X, c(2, 4)) ## another example.
collapse_mode(X, 4) #returns X