Fix equicoordinate quantile for mvnorm when p%in%c(0,1)

NEWS.md

@@ -12,6 +12,8 @@
   results correctly as matrices.
 * The `cdf()` method for `dist_multivariate_normal()` now gives the P(X <= q)
   rather than P(X > q) for consistency with all other `cdf()` methods.
+* The `quantile()` method for `dist_multivariate_normal()` now correctly gives
+  the boundaries when `p=0` or `p=1` when `type="equicoordinate"`.
 
 ## New features
 
@@ -30,7 +32,6 @@
 * `dist_mixture()` now displays the components of the mixture when the output
   width is sufficiently wide (@statasaurus, #112).
 
-
 ## Breaking changes
 
 * The `quantile()` method for `dist_multivariate_normal()` now defaults to 

R/dist_multivariate_normal.R

@@ -10,6 +10,7 @@
 #'
 #' @examples
 #' dist <- dist_multivariate_normal(mu = list(c(1,2)), sigma = list(matrix(c(4,2,2,3), ncol=2)))
+#' dimnames(dist) <- c("x", "y")
 #' dist
 #'
 #' @examplesIf requireNamespace("mvtnorm", quietly = TRUE)
@@ -62,7 +63,10 @@ quantile.dist_mvnorm <- function(x, p, type = c("equicoordinate", "marginal"),
                  sd = rep(diag(sqrt(x[["sigma"]])), each = length(p)), ...)
   } else {
     require_package("mvtnorm")
-    vapply(p, function(...) mvtnorm::qmvnorm(...)$quantile, numeric(1L), mean = x[["mu"]], sigma = x[["sigma"]], ...)
+    vapply(p, function(p, ...) {
+      if (p == 0) return(-Inf) else if (p == 1) return(Inf)
+      mvtnorm::qmvnorm(p, ...)$quantile
+    }, numeric(1L), mean = x[["mu"]], sigma = x[["sigma"]], ...)
   }
 
   matrix(q, nrow = length(p), ncol = dim(x))