geom_rect() can derive corners from x/width or y/height

NEWS.md

@@ -1,5 +1,8 @@
 # ggplot2 (development version)
 
+* `geom_rect()` can now derive the required corners positions from `x`/`width`
+ or `y`/`height` parameterisation (@teunbrand, #5861).
+
 # ggplot2 3.5.1
 
 This is a small release focusing on fixing regressions from 3.5.0 and 

R/geom-bar.R

@@ -129,6 +129,8 @@ geom_bar <- function(mapping = NULL, data = NULL,
 GeomBar <- ggproto("GeomBar", GeomRect,
  required_aes = c("x", "y"),
 
+ optional_aes = character(),
+
  # These aes columns are created by setup_data(). They need to be listed here so
  # that GeomRect$handle_na() properly removes any bars that fall outside the defined
  # limits, not just those for which x and y are outside the limits

R/geom-rect.R

@@ -31,7 +31,37 @@ GeomRect <- ggproto("GeomRect", Geom,
  default_aes = aes(colour = NA, fill = "grey35", linewidth = 0.5, linetype = 1,
  alpha = NA),
 
- required_aes = c("xmin", "xmax", "ymin", "ymax"),
+ optional_aes = c("x", "width", "xmin", "xmax", "y", "height", "ymin", "ymax"),
+ non_missing_aes = c("xmin", "xmax", "ymin", "ymax"),
+
+ setup_data = function(self, data, params) {
+ data$xmin <- data$xmin %||% params$xmin
+ data$xmax <- data$xmax %||% params$xmax
+ data$ymin <- data$ymin %||% params$ymin
+ data$ymax <- data$ymax %||% params$ymax
+ if (is.null(data$xmin) || is.null(data$xmax)) {
+ x <- resolve_rect(
+ data[["xmin"]], data[["xmax"]],
+ data[["x"]], data[["width"]] %||% params$width
+ )
+ i <- lengths(x) > 1
+ data[c("xmin", "xmax")[i]] <- x[i]
+ }
+ if (is.null(data$ymin) || is.null(data$ymax)) {
+ y <- resolve_rect(
+ data[["ymin"]], data[["ymax"]],
+ data[["y"]], data[["height"]] %||% params$height
+ )
+ i <- lengths(y) > 1
+ data[c("ymin", "ymax")[i]] <- y[i]
+ }
+ check_required_aesthetics(
+ self$non_missing_aes,
+ names(data),
+ snake_class(self)
+ )
+ data
+ },
 
  draw_panel = function(self, data, panel_params, coord, lineend = "butt", linejoin = "mitre") {
  data <- check_linewidth(data, snake_class(self))
@@ -73,3 +103,26 @@ GeomRect <- ggproto("GeomRect", Geom,
 
  rename_size = TRUE
 )
+
+resolve_rect <- function(min = NULL, max = NULL, center = NULL, length = NULL) {
+ if (is.null(min) && is.null(max)) {
+ min <- center - 0.5 * length
+ max <- center + 0.5 * length
+ return(list(min = min, max = max))
+ }
+ if (is.null(min)) {
+ if (is.null(center)) {
+ min <- max - length
+ } else {
+ min <- max - 2 * (max - center)
+ }
+ }
+ if (is.null(max)) {
+ if (is.null(center)) {
+ max <- min + length
+ } else {
+ max <- min + 2 * (center - min)
+ }
+ }
+ list(min = min, max = max)
+}

R/geom-tile.R

@@ -1,12 +1,11 @@
 #' Rectangles
 #'
 #' `geom_rect()` and `geom_tile()` do the same thing, but are
-#' parameterised differently: `geom_rect()` uses the locations of the four
-#' corners (`xmin`, `xmax`, `ymin` and `ymax`), while
-#' `geom_tile()` uses the center of the tile and its size (`x`,
-#' `y`, `width`, `height`). `geom_raster()` is a high
-#' performance special case for when all the tiles are the same size, and no
-#' pattern fills are applied.
+#' parameterised differently: `geom_tile()` uses the center of the tile and its
+#' size (`x`, `y`, `width`, `height`), while `geom_rect()` can use those or the
+#' locations of the corners (`xmin`, `xmax`, `ymin` and `ymax`).
+#' `geom_raster()` is a high performance special case for when all the tiles
+#' are the same size, and no pattern fills are applied.
 #'
 #' @eval rd_aesthetics("geom", "tile", "Note that `geom_raster()` ignores `colour`.")
 #' @inheritParams layer
@@ -15,11 +14,9 @@
 #' @export
 #'
 #' @details
-#' `geom_rect()` and `geom_tile()`'s respond differently to scale
-#' transformations due to their parameterisation. In `geom_rect()`, the scale
-#' transformation is applied to the corners of the rectangles. In `geom_tile()`,
-#' the transformation is applied only to the centres and its size is determined
-#' after transformation.
+#' Please note that the `width` and `height` aesthetics are not true position
+#' aesthetics and therefore are not subject to scale transformation. It is
+#' only after transformation that these aesthetics are applied.
 #'
 #' @examples
 #' # The most common use for rectangles is to draw a surface. You always want

tests/testthat/test-geom-rect.R

@@ -0,0 +1,36 @@
+test_that("geom_rect can derive corners", {
+
+ corners <- c("xmin", "xmax", "ymin", "ymax")
+ full <- data.frame(
+ xmin = c(1, 2), xmax = c(3, 6),
+ ymin = c(1, 2), ymax = c(3, 6),
+ width = c(2, 4), height = c(2, 4),
+ x = c(2, 4), y = c(2, 4)
+ )
+
+ test <- full[, c("xmin", "ymin", "width", "height")]
+ test <- GeomRect$setup_data(test, NULL)
+ expect_equal(full[, corners], test[, corners])
+
+ test <- full[, c("xmin", "ymin", "x", "y")]
+ test <- GeomRect$setup_data(test, NULL)
+ expect_equal(full[, corners], test[, corners])
+
+ test <- full[, c("x", "y", "width", "height")]
+ test <- GeomRect$setup_data(test, NULL)
+ expect_equal(full[, corners], test[, corners])
+
+ test <- full[, c("xmax", "ymax", "width", "height")]
+ test <- GeomRect$setup_data(test, NULL)
+ expect_equal(full[, corners], test[, corners])
+
+ test <- full[, c("xmax", "ymax", "x", "y")]
+ test <- GeomRect$setup_data(test, NULL)
+ expect_equal(full[, corners], test[, corners])
+
+ test <- full[, c("x", "y")]
+ expect_error(
+ GeomRect$setup_data(test, NULL),
+ "requires the following missing aesthetics"
+ )
+})