Added coercion of matrix/array versions of mu and sigma, re. #18.

R/as.theta.R

@@ -1,12 +1,17 @@
 #' Coerce a list to a theta object
 #'
-#' @description At the moment, only the class is added.
+#' First, the class is added. Next, matrix means and array covariances are
+#' coerced to list form.
+#' Covariances on array form are assumed to be \code{d} by \code{d} by \code{m}.
+#' Means on matrix form are as assumed to be \code{d} by \code{m}. I.e.
+#' rows correspond to the dimensions and colums to components, or the mean vectors
+#' as column vectors.
 #'
 #' @param x A theta-like object that can be coerced.
 #' @return A theta object. See \code{\link{rtheta}}.
 #' @examples
 #' m <- 2
-#' d <- 2
+#' d <- 3
 #' x <- list(m = m,
 #'           d = d,
 #'           pie = c(0.5, 0.5),
@@ -15,9 +20,33 @@
 #' print(x)
 #' theta <- as.theta(x)
 #' print(theta)
+#'
+#' x2 <- list(m = m,
+#'            d = d,
+#'            pie = c(0.5, 0.5),
+#'            mu = simplify2array(list(comp1=rep(0,d), comp2=rep(1,d))),
+#'            sigma = simplify2array(list(comp1=diag(d), comp2=diag(d))))
+#' theta2 <- as.theta(x2)
+#' print(theta2)
 #' @export
 as.theta <- function(x) {
   class(x) <- "theta"
+
+  # Convert 'matrix' means to list
+  if (is.matrix(x[[4]]) && is.numeric(x[[4]])) {
+    stopifnot(nrow(x[[4]]) == x[[2]], # d
+              ncol(x[[4]]) == x[[1]]) # m
+    x[[4]] <- structure(lapply(seq_len(x[[1]]), function(j) x[[4]][, j]),
+                        names = colnames(x[[4]]))
+  }
+
+  # Convert higher order array covariances to list
+  if (is.array(x[[5]]) && is.numeric(x[[5]])) {
+    stopifnot(dim(x[[5]]) == c(x[[2]], x[[2]], x[[1]]))
+    x[[5]] <- structure(lapply(seq_len(x[[1]]), function(k) x[[5]][, , k]),
+                        names = dimnames(x[[5]])[[3]])
+  }
+
   if (is.theta(x)) {
     return(x)
   } else {

tests/testthat/test-as.theta.R

@@ -12,3 +12,15 @@ test_that("Check that as.theta works as intended", {
   expect_true(is.theta(as.theta(x)))
   suppressWarnings(expect_error(as.theta(x[-4])))
 })
+
+# Coercion tests
+d <- 3
+x2 <- list(m = m,
+           d = d,
+           pie = c(0.5, 0.5),
+           mu = simplify2array(list(comp1 = rep(0,d), comp2 = rep(1,d))),
+           sigma = simplify2array(list(comp1 = diag(d), comp2 = diag(d))))
+
+test_that("Check that as.theta works for 'matrix means'", {
+  expect_true(is.theta(as.theta(x2)))
+})