facet_grid(space = "free") can work with coord_fixed() (#5977)

* allow coord aspect ratio when space is free

* add test

* add news bullet

NEWS.md

@@ -154,6 +154,8 @@
  (@teunbrand, #5945).
 * (internal) The summary function of `stat_summary()` and `stat_summary_bin()` 
  is setup once in total instead of once per group (@teunbrand, #5971)
+* `facet_grid(space = "free")` can now be combined with `coord_fixed()` 
+ (@teunbrand, #4584).
 
 # ggplot2 3.5.1
 

R/facet-.R

@@ -139,18 +139,22 @@ Facet <- ggproto("Facet", NULL,
  free <- params$free %||% list(x = FALSE, y = FALSE)
  space <- params$space_free %||% list(x = FALSE, y = FALSE)
 
- if ((free$x || free$y) && !coord$is_free()) {
- cli::cli_abort(
- "{.fn {snake_class(self)}} can't use free scales with \\
- {.fn {snake_class(coord)}}."
- )
- }
-
  aspect_ratio <- theme$aspect.ratio
  if (!is.null(aspect_ratio) && (space$x || space$y)) {
  cli::cli_abort("Free scales cannot be mixed with a fixed aspect ratio.")
  }
 
+ if (!coord$is_free()) {
+ if (space$x && space$y) {
+ aspect_ratio <- aspect_ratio %||% coord$ratio
+ } else if (free$x || free$y) {
+ cli::cli_abort(
+ "{.fn {snake_class(self)}} can't use free scales with \\
+ {.fn {snake_class(coord)}}."
+ )
+ }
+ }
+
  table <- self$init_gtable(
  panels, layout, theme, ranges, params,
  aspect_ratio = aspect_ratio %||% coord$aspect(ranges[[1]])
@@ -219,7 +223,7 @@ Facet <- ggproto("Facet", NULL,
  if (space$y) {
  idx <- layout$PANEL[layout$COL == 1]
  heights <- vapply(idx, function(i) diff(ranges[[i]]$y.range), numeric(1))
- heights <- unit(heights, "null")
+ heights <- unit(heights * abs(aspect_ratio %||% 1), "null")
  }
 
  # Build gtable

tests/testthat/test-facet-layout.R

@@ -253,6 +253,23 @@ test_that("facet_grid throws errors at bad layout specs", {
  expect_snapshot_error(ggplotGrob(p))
 })
 
+test_that("facet_grid can respect coord aspect with free scales/space", {
+ df <- expand.grid(x = letters[1:6], y = LETTERS[1:3])
+ p <- ggplot(df, aes(x, y)) +
+ geom_tile() +
+ facet_grid(
+ rows = vars(y == "C"),
+ cols = vars(x %in% c("e", "f")),
+ scales = "free", space = "free"
+ ) +
+ coord_fixed(3, expand = FALSE)
+ gt <- ggplotGrob(p)
+ width <- gt$widths[panel_cols(gt)$l]
+ height <- gt$heights[panel_rows(gt)$t]
+ expect_equal(as.numeric(width), c(4, 2))
+ expect_equal(as.numeric(height), c(6, 3))
+})
+
 test_that("facet_wrap and facet_grid throws errors when using reserved words", {
  mtcars2 <- mtcars
  mtcars2$PANEL <- mtcars2$cyl