R/var2.R

In cstubben/popbio: Construction and Analysis of Matrix Population Models

#' Variance matrix
#'
#' Calculates the variances from a list of matrices
#'
#' @param x A list of two or more matrices
#'
#' @return A matrix containing variances
#'
#' @author Chris Stubben
#'
#' @examples
#' var2(hudsonia)
#'
#' @export

var2 <- function(x) {
  if (!all(sapply(x, is.matrix))) {
    stop("'x' must be a list containing matrices")
  }
  dims <- sapply(x, dim)
  n <- dims[1, 1]
  p <- dims[2, 1]
  if (!all(n == dims[1, ]) || !all(p == dims[2, ])) {
    stop("the matrices must have the same dimensions")
  }
  mat <- matrix(unlist(x), n * p, length(x))
  mm <- matrix(apply(mat, 1, var), n, p)
  dimnames(mm) <- dimnames(x[[1]])
  mm
}