Add ggridges plots

DESCRIPTION

@@ -64,10 +64,7 @@ Suggests:
     rmarkdown,
     testthat,
     crosstalk,
-    knitr,
-    spelling,
-    emmeans,
-    vdiffr
+    ggridges
 Roxygen: list(markdown = TRUE)
 RoxygenNote: 7.3.2
 SystemRequirements: openssl

NAMESPACE

@@ -42,6 +42,7 @@ export(ggally_cross)
 export(ggally_crosstable)
 export(ggally_density)
 export(ggally_densityDiag)
+export(ggally_density_ridges)
 export(ggally_denstrip)
 export(ggally_diagAxis)
 export(ggally_dot)

R/gg-plots.R

@@ -1655,6 +1655,34 @@ ggally_naDiag <- function(...) {
   ggally_na(...)
 }
 
+#' Create a ridgeline plot.
+#'
+#' `ggally_density_ridges` generates a ridgeline plot with partially overlapping line plots that create the impression of a mountain range. They can be quite useful for visualizing changes in distributions over time or space.
+#'
+#' @param data The data set used.
+#' @param mapping The aesthetics used.
+#' @param ... Other parameters passed on to \code{\link[ggridges]{geom_density_ridges2}}.
+#'
+#' @examples
+#'   data(iris)
+#'   ggpairs(iris, lower = list("combo" = ggally_density_ridges))
+#'   ggpairs(iris, lower = list("combo" = ggally_density_ridges, mapping = ggplot2::aes(color = Species)))
+#'   ggpairs(iris, lower = list("combo" = wrap(ggally_density_ridges, rel_min_height = 0.01), mapping = ggplot2::aes(color = Species)))
+#'
+#' @author Jens Preussner \email{jens.preussner@@mpi-bn.mpg.de}
+#' @export
+ggally_density_ridges <- function(data, mapping, ..., scale = 1) {
+  require_namespaces("ggridges")
+  horizontal <- GGally:::is_horizontal(data, mapping)
+
+  if (!horizontal) {
+    mapping <- GGally:::mapping_swap_x_y(mapping)
+  }
+
+  mapping <- GGally:::mapping_color_to_fill(mapping)
+
+  ggplot2::ggplot(data) +
+    ggridges::geom_density_ridges2(mapping, ..., scale = scale)
 
 
 #' Scatterplot for continuous and categorical variables

tests/testthat/test-zzz_ggpairs.R

@@ -724,7 +724,7 @@ test_that("subtypes", {
   )
   comSubs <- list(
     "autopoint",
-    "box", "dot", "box_no_facet", "dot_no_facet",
+    "box", "dot", "box_no_facet", "dot_no_facet", "density_ridges",
     wrap("facethist", binwidth = 1),
     "facetdensity",
     "facetdensitystrip",