export labels class

Author: teunbrand

NAMESPACE

@@ -291,6 +291,7 @@ export(calc_element)
 export(check_device)
 export(class_ggplot)
 export(class_ggplot_built)
+export(class_labels)
 export(class_mapping)
 export(class_theme)
 export(combine_vars)

R/labels.R

@@ -175,22 +175,49 @@ setup_plot_labels <- function(plot, layers, data) {
 #' p +
 #'  labs(title = "title") +
 #'  labs(title = NULL)
-labs <- S7::new_class(
-  "labels", parent = S7::new_S3_class("gg"),
-  constructor = function(..., title = waiver(), subtitle = waiver(),
-                         caption = waiver(), tag = waiver(), dictionary = waiver(),
-                         alt = waiver(), alt_insight = waiver()) {
-    # .ignore_empty = "all" is needed to allow trailing commas, which is NOT a trailing comma for dots_list() as it's in ...
-    args <- dots_list(..., title = title, subtitle = subtitle, caption = caption,
-                      tag = tag, alt = allow_lambda(alt), alt_insight = alt_insight,
-                      dictionary = dictionary, .ignore_empty = "all")
+labs <- function(..., title = waiver(), subtitle = waiver(),
+                 caption = waiver(), tag = waiver(), dictionary = waiver(),
+                 alt = waiver(), alt_insight = waiver()) {
+  # .ignore_empty = "all" is needed to allow trailing commas, which is NOT a trailing comma for dots_list() as it's in ...
+  args <- dots_list(..., title = title, subtitle = subtitle, caption = caption,
+                    tag = tag, alt = allow_lambda(alt), alt_insight = alt_insight,
+                    dictionary = dictionary, .ignore_empty = "all")
+
+  is_waive <- vapply(args, is.waiver, logical(1))
+  args <- args[!is_waive]
+  # remove duplicated arguments
+  args <- args[!duplicated(names(args))]
+  args <- rename_aes(args)
+  class_labels(args)
+}
 
-    is_waive <- vapply(args, is.waiver, logical(1))
-    args <- args[!is_waive]
-    # remove duplicated arguments
-    args <- args[!duplicated(names(args))]
-    args <- rename_aes(args)
-    S7::new_object(args)
+#' The labels class
+#'
+#' The labels class holds a list with label information to display as titles
+#' of plot components. The preferred way to construct an object of the labels
+#' class is to use the [`labs()`] function.
+#'
+#' @param labels A named list.
+#'
+#' @export
+class_labels <- S7::new_class(
+  "labels", parent = S7::new_S3_class("gg"),
+  constructor = function(labels) {
+    S7::new_object(labels)
+  },
+  validator = function(self) {
+    if (!is.list(self)) {
+      return("labels must be a list.")
+    }
+    if (!is_named2(self)) {
+      return("every label must be named.")
+    }
+    dups <- unique(names(self)[duplicated(names(self))])
+    if (length(dups) > 0) {
+      dups <- oxford_comma(dups, final = "and")
+      return(paste0("labels cannot contain duplicate names (", dups, ")."))
+    }
+    return(NULL)
   }
 )
 

R/plot-construction.R

@@ -147,7 +147,7 @@ S7::method(ggplot_add, list(class_scale, class_ggplot)) <-
     plot
   }
 
-S7::method(ggplot_add, list(labs, class_ggplot)) <-
+S7::method(ggplot_add, list(class_labels, class_ggplot)) <-
   function(object, plot, ...) { update_labels(plot, object) }
 
 S7::method(ggplot_add, list(class_guides, class_ggplot)) <-

R/plot.R

@@ -34,7 +34,7 @@ class_ggplot <- S7::new_class(
     coordinates = class_coord,
     facet   = class_facet,
     layout  = class_layout,
-    labels  = labs,
+    labels  = class_labels,
     plot_env = S7::class_environment
   ),
   constructor = function(data = waiver(), layers = list(), scales = NULL,