Fix limits argument of scale_{colour,fill}_manual()

NEWS.md

@@ -122,6 +122,9 @@
 * `stat_summary()` and related functions now support rlang-style lambda functions
   (#3568, @dkahle).
 
+* `scale_manual_*(limits = ...)` now actually limits the scale (#3262,
+  @yutannihilation).
+
 
 # ggplot2 3.2.1
 

R/scale-.r

@@ -775,11 +775,16 @@ ScaleDiscrete <- ggproto("ScaleDiscrete", Scale,
       self$n.breaks.cache <- n
     }
 
-    if (is.null(names(pal))) {
-      pal_match <- pal[match(as.character(x), limits)]
-    } else {
+    if (is_named(pal)) {
+      # if pal is named, limit the pal by the names first,
+      # then limit the values by the pal
+      idx_nomatch <- is.na(match(names(pal), limits))
+      pal[idx_nomatch] <- NA
       pal_match <- pal[match(as.character(x), names(pal))]
       pal_match <- unname(pal_match)
+    } else {
+      # if pal is not named, limit the values directly
+      pal_match <- pal[match(as.character(x), limits)]
     }
 
     if (self$na.translate) {

tests/testthat/test-scale-manual.r

@@ -85,3 +85,15 @@ test_that("unnamed values match breaks in manual scales", {
   s$train(c("data_red", "data_black"))
   expect_equal(s$map(c("data_red", "data_black")), c("red", "black"))
 })
+
+test_that("limits works (#3262)", {
+  # named charachter vector
+  s1 <- scale_colour_manual(values = c("8" = "c", "4" = "a", "6" = "b"), limits = c("4", "8"))
+  s1$train(c("4", "6", "8"))
+  expect_equal(s1$map(c("4", "6", "8")), c("a", NA, "c"))
+
+  # named charachter vector
+  s2 <- scale_colour_manual(values = c("c", "a", "b"), limits = c("4", "8"))
+  s2$train(c("4", "6", "8"))
+  expect_equal(s2$map(c("4", "6", "8")), c("c", NA, "a"))
+})