Make make_labels() more consistent (#2981)

Author: yutannihilation

NEWS.md

@@ -2,6 +2,9 @@
 
 *   `geom_rug()` now works with `coord_flip()` (@has2k1, #2987).
 
+* Default labels are now generated more consistently; e.g., symbols no longer
+  get backticks, and long expressions are abbreviated with `...`
+  (@yutannihilation, #2981).
 
 # ggplot2 3.1.0
 

R/aes-calculated.r

@@ -87,16 +87,19 @@ strip_dots <- function(expr) {
 # Convert aesthetic mapping into text labels
 make_labels <- function(mapping) {
   default_label <- function(aesthetic, mapping) {
-    # e.g., geom_smooth(aes(colour = "loess"))
+    # e.g., geom_smooth(aes(colour = "loess")) or aes(y = NULL)
     if (is.atomic(mapping)) {
-      aesthetic
+      return(aesthetic)
+    }
+
+    mapping <- strip_dots(mapping)
+    if (rlang::is_quosure(mapping) && rlang::quo_is_symbol(mapping)) {
+      name <- rlang::as_string(rlang::quo_get_expr(mapping))
     } else {
-      x <- rlang::quo_text(strip_dots(mapping))
-      if (length(x) > 1) {
-        x <- paste0(x[[1]], "...")
-      }
-      x
+      name <- rlang::quo_text(mapping)
+      name <- gsub("\n.*$", "...", name)
     }
+    name
   }
   Map(default_label, names(mapping), mapping)
 }

R/plot-construction.r

@@ -123,7 +123,7 @@ ggplot_add.uneval <- function(object, plot, object_name) {
   # defaults() doesn't copy class, so copy it.
   class(plot$mapping) <- class(object)
 
-  labels <- lapply(object, function(x) if (is.null(x)) x else rlang::quo_name(x))
+  labels <- make_labels(object)
   names(labels) <- names(object)
   update_labels(plot, labels)
 }

tests/testthat/test-aes-calculated.r

@@ -24,7 +24,18 @@ test_that("strip_dots remove dots around calculated aesthetics", {
   )
 })
 
-test_that("calculation stripped from labels", {
-  expect_equal(make_labels(aes(x = ..y..)), list(x = "y"))
-  expect_equal(make_labels(aes(x = stat(y))), list(x = "y"))
+test_that("make_labels() deprases mappings properly", {
+  # calculation stripped from labels
+  expect_identical(make_labels(aes(x = ..y..)), list(x = "y"))
+  expect_identical(make_labels(aes(x = stat(y))), list(x = "y"))
+
+  # symbol is always deparsed without backticks
+  expect_identical(make_labels(aes(x = `a b`)), list(x = "a b"))
+  # long expression is abbreviated with ...
+  x_lab <- make_labels(aes(x = 2 * x * exp(`coef 1` * x^2) * 2 * x * exp(`coef 1` * x^2) * 2 * x))$x
+  expect_length(x_lab, 1L)
+  expect_match(x_lab, "...$")
+  # if the mapping is a literal or NULL, the aesthetics is used
+  expect_identical(make_labels(aes(x = 1)), list(x = "x"))
+  expect_identical(make_labels(aes(x = NULL)), list(x = "x"))
 })

tests/testthat/test-aes.r

@@ -95,7 +95,7 @@ test_that("quosures are squashed when creating default label for a mapping", {
 
 test_that("labelling doesn't cause error if aesthetic is NULL", {
   p <- ggplot(mtcars) + aes(x = NULL)
-  expect_null(p$labels$x)
+  expect_identical(p$labels$x, "x")
 })
 
 test_that("aes standardises aesthetic names", {