asplit() added in R 3.6.0

[tstev]

A new base::asplit function was added in 3.6.0 which would bump up Depends: R (>=3.6.0).

The new function asplit() allow splitting an array or matrix by its margins.

It is defined as follows:

function (x, MARGIN) 
{
    dl <- length(dim(x))
    if (!dl) 
        stop("dim(x) must have a positive length")
    if (is.object(x)) 
        x <- if (dl == 2L) 
            as.matrix(x)
        else as.array(x)
    d <- dim(x)
    dn <- dimnames(x)
    ds <- seq_len(dl)
    if (is.character(MARGIN)) {
        if (is.null(dnn <- names(dn))) 
            stop("'x' must have named dimnames")
        MARGIN <- match(MARGIN, dnn)
        if (anyNA(MARGIN)) 
            stop("not all elements of 'MARGIN' are names of dimensions")
    }
    s.call <- ds[-MARGIN]
    s.ans <- ds[MARGIN]
    d.call <- d[-MARGIN]
    d.ans <- d[MARGIN]
    dn.call <- dn[-MARGIN]
    dn.ans <- dn[MARGIN]
    d2 <- prod(d.ans)
    newx <- aperm(x, c(s.call, s.ans))
    dim(newx) <- c(prod(d.call), d2)
    ans <- vector("list", d2)
    for (i in seq_len(d2)) {
        ans[[i]] <- array(newx[, i], d.call, dn.call)
    }
    array(ans, d.ans, dn.ans)
}