Free scales for coord_polar() (#5354)

* `coord_polar()` can have free scales

* Add test

* Add NEWS bullet

* `coord_radial()` is also free

Author: teunbrand

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* `coord_polar()` can have free scales in facets (@teunbrand, #2815).
+
 * The new argument `axes` in `facet_grid()` and `facet_wrap()` controls the
   display of axes at interior panel positions. Additionally, the `axis.labels`
   argument can be used to only draw tick marks or fully labelled axes 

R/coord-polar.R

@@ -80,6 +80,8 @@ CoordPolar <- ggproto("CoordPolar", Coord,
 
   aspect = function(details) 1,
 
+  is_free = function() TRUE,
+
   distance = function(self, x, y, details) {
     arc <- self$start + c(0, 2 * pi)
     dir <- self$direction

R/coord-radial.R

@@ -79,6 +79,8 @@ CoordRadial <- ggproto("CoordRadial", Coord,
     diff(details$bbox$y) / diff(details$bbox$x)
   },
 
+  is_free = function() TRUE,
+
   distance = function(self, x, y, details) {
     arc <- details$arc %||% c(0, 2 * pi)
     if (self$theta == "x") {

R/facet-grid-.R

@@ -369,9 +369,7 @@ FacetGrid <- ggproto("FacetGrid", Facet,
     if (!is.null(aspect_ratio) && (params$space_free$x || params$space_free$y)) {
       cli::cli_abort("Free scales cannot be mixed with a fixed aspect ratio.")
     }
-    if (is.null(aspect_ratio) && !params$free$x && !params$free$y) {
-      aspect_ratio <- coord$aspect(ranges[[1]])
-    }
+    aspect_ratio <- aspect_ratio %||% coord$aspect(ranges[[1]])
     if (is.null(aspect_ratio)) {
       aspect_ratio <- 1
       respect <- FALSE

R/facet-wrap.R

@@ -293,12 +293,9 @@ FacetWrap <- ggproto("FacetWrap", Facet,
       structure(labels_df, type = "cols"),
       params$labeller, theme)
 
-    # If user hasn't set aspect ratio, and we have fixed scales, then
-    # ask the coordinate system if it wants to specify one
-    aspect_ratio <- theme$aspect.ratio
-    if (is.null(aspect_ratio) && !params$free$x && !params$free$y) {
-      aspect_ratio <- coord$aspect(ranges[[1]])
-    }
+    # If user hasn't set aspect ratio, ask the coordinate system if
+    # it wants to specify one
+    aspect_ratio <- theme$aspect.ratio %||% coord$aspect(ranges[[1]])
 
     if (is.null(aspect_ratio)) {
       aspect_ratio <- 1

tests/testthat/test-coord-polar.R

@@ -79,6 +79,25 @@ test_that("Inf is squished to range", {
   expect_equal(d[[3]]$theta, mapped_discrete(0))
 })
 
+test_that("coord_polar can have free scales in facets", {
+
+  p <- ggplot(data_frame0(x = c(1, 2)), aes(1, x)) +
+    geom_col() +
+    coord_polar(theta = "y")
+
+  sc <- layer_scales(p + facet_wrap(~ x), 1, 1)
+  expect_equal(sc$y$get_limits(), c(0, 2))
+
+  sc <- layer_scales(p + facet_wrap(~ x, scales = "free"), 1, 1)
+  expect_equal(sc$y$get_limits(), c(0, 1))
+
+  sc <- layer_scales(p + facet_grid(x ~ .), 1, 1)
+  expect_equal(sc$y$get_limits(), c(0, 2))
+
+  sc <- layer_scales(p + facet_grid(x ~ ., scales = "free"), 1, 1)
+  expect_equal(sc$y$get_limits(), c(0, 1))
+})
+
 test_that("coord_radial warns about axes", {
 
   p <- ggplot(mtcars, aes(disp, mpg)) +