Make facet section of summary() more terse (#6074)

* print facets vars instead of whole object

* add test

* add news bullet

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* The `summary()` method for ggplots is now more terse about facets 
+ (@teunbrand, #5989).
 * `guide_bins()`, `guide_colourbar()` and `guide_coloursteps()` gain an `angle`
  argument to overrule theme settings, similar to `guide_axis(angle)` 
  (@teunbrand, #4594).

R/summary.R

@@ -29,8 +29,9 @@ summary.ggplot <- function(object, ...) {
  cat("scales: ", paste(object$scales$input(), collapse = ", "), "\n")
  }
 
- cat("faceting: ")
- print(object$facet)
+ vars <- object$facet$vars()
+ vars <- if (length(vars) > 0) paste0("~", vars) else "<empty>"
+ cat("faceting: ", paste0(vars, collapse = ", "), "\n")
 
  if (length(object$layers) > 0)
  cat("-----------------------------------\n")

tests/testthat/_snaps/utilities.md

@@ -54,3 +54,19 @@
 
  Can't recycle `..1` (size 4) to match `..2` (size 0).
 
+# summary method gives a nice summary
+
+ Code
+  summary(p)
+ Output
+  data: manufacturer, model, displ, year, cyl, trans, drv, cty, hwy, fl,
+  class [234x11]
+  mapping: x = ~displ, y = ~hwy, colour = ~drv
+  scales: x, xmin, xmax, xend, xintercept, xmin_final, xmax_final, xlower, xmiddle, xupper, x0, colour 
+  faceting: ~year, ~cyl 
+  -----------------------------------
+  geom_point: na.rm = FALSE
+  stat_identity: na.rm = FALSE
+  position_identity 
+  
+

tests/testthat/test-utilities.R

@@ -196,3 +196,16 @@ test_that("expose/ignore_data() can round-trip a data.frame", {
  expect_equal(test, df[, c("a", "c", "b", "d")])
 
 })
+
+test_that("summary method gives a nice summary", {
+ # This test isn't important enough to break anything on CRAN
+ skip_on_cran()
+
+ p <- ggplot(mpg, aes(displ, hwy, colour = drv)) +
+ geom_point() +
+ scale_x_continuous() +
+ scale_colour_brewer() +
+ facet_grid(year ~ cyl)
+
+ expect_snapshot(summary(p))
+})