Repurpose coord expansion (#6027)

* `default_expansion()` handles longer `expand` arg

* Parser for expand argument

* insert parser at relevant places

* Use Coord$setup_params() to setup expand

* fix plot helper not including params

* Redocument parameter

* fix `coord_flip()` case

* add test

* add news bullet

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* `coord_*(expand)` can now take a logical vector to control expansion at any
+ side of the panel (top, right, bottom, left) (@teunbrand, #6020)
 * (Breaking) The defaults for all geoms can be set at one in the theme. 
  (@teunbrand based on pioneering work by @dpseidel, #2239)
  * A new `theme(geom)` argument is used to track these defaults.

R/coord-.R

@@ -184,10 +184,11 @@ Coord <- ggproto("Coord",
  # Will generally have to return FALSE for coordinate systems that enforce a fixed aspect ratio.
  is_free = function() FALSE,
 
- setup_params = function(data) {
+ setup_params = function(self, data) {
  list(
  guide_default = guide_axis(),
- guide_missing = guide_none()
+ guide_missing = guide_none(),
+ expand = parse_coord_expand(self$expand %||% TRUE)
  )
  },
 
@@ -243,6 +244,26 @@ render_axis <- function(panel_params, axis, scale, position, theme) {
  }
 }
 
+# Elaborates an 'expand' argument for every side (top, right, bottom or left)
+parse_coord_expand <- function(expand) {
+ check_logical(expand)
+ if (anyNA(expand)) {
+ cli::cli_abort("{.arg expand} cannot contain missing values.")
+ }
+
+ if (!is_named(expand)) {
+ return(rep_len(expand, 4))
+ }
+
+ # Match by top/right/bottom/left
+ out <- rep(TRUE, 4)
+ i <- match(names(expand), .trbl)
+ if (sum(!is.na(i)) > 0) {
+ out[i] <- unname(expand)[!is.na(i)]
+ }
+ out
+}
+
 # Utility function to check coord limits
 check_coord_limits <- function(
  limits, arg = caller_arg(limits), call = caller_env()

R/coord-cartesian-.R

@@ -9,6 +9,10 @@
 #' @param expand If `TRUE`, the default, adds a small expansion factor to
 #' the limits to ensure that data and axes don't overlap. If `FALSE`,
 #' limits are taken exactly from the data or `xlim`/`ylim`.
+#' Giving a logical vector will separately control the expansion for the four
+#' directions (top, left, bottom and right). The `expand` argument will be
+#' recycled to length 4 if necessary. Alternatively, can be a named logical
+#' vector to control a single direction, e.g. `expand = c(bottom = FALSE)`.
 #' @param default Is this the default coordinate system? If `FALSE` (the default),
 #' then replacing this coordinate system with another one creates a message alerting
 #' the user that the coordinate system is being replaced. If `TRUE`, that warning
@@ -100,8 +104,8 @@ CoordCartesian <- ggproto("CoordCartesian", Coord,
 
  setup_panel_params = function(self, scale_x, scale_y, params = list()) {
  c(
- view_scales_from_scale(scale_x, self$limits$x, self$expand),
- view_scales_from_scale(scale_y, self$limits$y, self$expand)
+ view_scales_from_scale(scale_x, self$limits$x, params$expand[c(4, 2)]),
+ view_scales_from_scale(scale_y, self$limits$y, params$expand[c(3, 1)])
  )
  },
 

R/coord-flip.R

@@ -89,6 +89,7 @@ CoordFlip <- ggproto("CoordFlip", CoordCartesian,
  },
 
  setup_panel_params = function(self, scale_x, scale_y, params = list()) {
+ params$expand <- params$expand[c(2, 1, 4, 3)]
  parent <- ggproto_parent(CoordCartesian, self)
  panel_params <- parent$setup_panel_params(scale_x, scale_y, params)
  flip_axis_labels(panel_params)

R/coord-radial.R

@@ -66,7 +66,6 @@ coord_radial <- function(theta = "x",
  check_bool(r.axis.inside, allow_null = TRUE)
  }
 
- check_bool(expand)
  check_bool(rotate.angle)
  check_number_decimal(start, allow_infinite = FALSE)
  check_number_decimal(end, allow_infinite = FALSE, allow_null = TRUE)
@@ -139,8 +138,8 @@ CoordRadial <- ggproto("CoordRadial", Coord,
  setup_panel_params = function(self, scale_x, scale_y, params = list()) {
 
  params <- c(
- view_scales_polar(scale_x, self$theta, expand = self$expand),
- view_scales_polar(scale_y, self$theta, expand = self$expand),
+ view_scales_polar(scale_x, self$theta, expand = params$expand[c(4, 2)]),
+ view_scales_polar(scale_y, self$theta, expand = params$expand[c(3, 1)]),
  list(bbox = polar_bbox(self$arc, inner_radius = self$inner_radius),
  arc = self$arc, inner_radius = self$inner_radius)
  )
@@ -469,27 +468,27 @@ CoordRadial <- ggproto("CoordRadial", Coord,
  },
 
  setup_params = function(self, data) {
- if (isFALSE(self$r_axis_inside)) {
- place <- in_arc(c(0, 0.5, 1, 1.5) * pi, self$arc)
- if (place[1]) {
- return(list(r_axis = "left", fake_arc = c(0, 2) * pi))
- }
- if (place[3]) {
- return(list(r_axis = "left", fake_arc = c(1, 3)* pi))
- }
- if (place[2]) {
- return(list(r_axis = "bottom", fake_arc = c(0.5, 2.5) * pi))
- }
- if (place[4]) {
- return(list(r_axis = "bottom", fake_arc = c(1.5, 3.5) * pi))
- }
+ params <- ggproto_parent(Coord, self)$setup_params(data)
+ if (!isFALSE(self$r_axis_inside)) {
+ return(params)
+ }
+
+ place <- in_arc(c(0, 0.5, 1, 1.5) * pi, self$arc)
+ if (!any(place)) {
  cli::cli_warn(c(
  "No appropriate placement found for {.arg r_axis_inside}.",
  i = "Axis will be placed at panel edge."
  ))
- self$r_axis_inside <- TRUE
+ params$r_axis_inside <- TRUE
+ return(params)
  }
- return(NULL)
+
+ params$r_axis <- if (any(place[c(1, 3)])) "left" else "bottom"
+ params$fake_arc <- switch(
+ which(place[c(1, 3, 2, 4)])[1],
+ c(0, 2), c(1, 3), c(0.5, 2.5), c(1.5, 3.5)
+ ) * pi
+ params
  }
 )
 

R/coord-sf.R

@@ -18,12 +18,10 @@ CoordSf <- ggproto("CoordSf", CoordCartesian,
  },
 
  setup_params = function(self, data) {
- crs <- self$determine_crs(data)
+ params <- ggproto_parent(Coord, self)$setup_params(data)
 
- params <- list(
- crs = crs,
- default_crs = self$default_crs
- )
+ params$crs <- self$determine_crs(data)
+ params$default_crs <- self$default_crs
  self$params <- params
 
  params
@@ -170,8 +168,8 @@ CoordSf <- ggproto("CoordSf", CoordCartesian,
 
  setup_panel_params = function(self, scale_x, scale_y, params = list()) {
  # expansion factors for scale limits
- expansion_x <- default_expansion(scale_x, expand = self$expand)
- expansion_y <- default_expansion(scale_y, expand = self$expand)
+ expansion_x <- default_expansion(scale_x, expand = params$expand[c(4, 2)])
+ expansion_y <- default_expansion(scale_y, expand = params$expand[c(3, 1)])
 
  # get scale limits and coord limits and merge together
  # coord limits take precedence over scale limits

R/coord-transform.R

@@ -153,8 +153,8 @@ CoordTrans <- ggproto("CoordTrans", Coord,
 
  setup_panel_params = function(self, scale_x, scale_y, params = list()) {
  c(
- view_scales_from_scale_with_coord_trans(scale_x, self$limits$x, self$trans$x, self$expand),
- view_scales_from_scale_with_coord_trans(scale_y, self$limits$y, self$trans$y, self$expand)
+ view_scales_from_scale_with_coord_trans(scale_x, self$limits$x, self$trans$x, params$expand[c(4, 2)]),
+ view_scales_from_scale_with_coord_trans(scale_y, self$limits$y, self$trans$y, params$expand[c(3, 1)])
  )
  },
 

R/scale-expansion.R

@@ -98,11 +98,24 @@ expand_range4 <- function(limits, expand) {
 #'
 default_expansion <- function(scale, discrete = expansion(add = 0.6),
  continuous = expansion(mult = 0.05), expand = TRUE) {
- if (!expand) {
- return(expansion(0, 0))
+ out <- expansion()
+ if (!any(expand)) {
+ return(out)
  }
+ scale_expand <- scale$expand %|W|%
+ if (scale$is_discrete()) discrete else continuous
 
- scale$expand %|W|% if (scale$is_discrete()) discrete else continuous
+ # for backward compatibility, we ensure expansions have expected length
+ expand <- rep_len(expand, 2L)
+ scale_expand <- rep_len(scale_expand, 4)
+
+ if (expand[1]) {
+ out[1:2] <- scale_expand[1:2]
+ }
+ if (expand[2]) {
+ out[3:4] <- scale_expand[3:4]
+ }
+ out
 }
 
 #' Expand limits in (possibly) transformed space

tests/testthat/helper-plot-data.R

@@ -5,7 +5,7 @@ cdata <- function(plot) {
  lapply(pieces$data, function(d) {
  dapply(d, "PANEL", function(panel_data) {
  scales <- pieces$layout$get_scales(panel_data$PANEL[1])
- panel_params <- plot$coordinates$setup_panel_params(scales$x, scales$y)
+ panel_params <- plot$coordinates$setup_panel_params(scales$x, scales$y, params = pieces$layout$coord_params)
  plot$coordinates$transform(panel_data, panel_params)
  })
  })

tests/testthat/test-coord-.R

@@ -75,3 +75,19 @@ test_that("coords append a column to the layout correctly", {
  expect_equal(test$COORD, c(1, 2, 1))
 })
 
+test_that("coord expand takes a vector", {
+
+ base <- ggplot() + lims(x = c(0, 10), y = c(0, 10))
+
+ p <- ggplot_build(base + coord_cartesian(expand = c(TRUE, FALSE, FALSE, TRUE)))
+ pp <- p$layout$panel_params[[1]]
+ expect_equal(pp$x.range, c(-0.5, 10))
+ expect_equal(pp$y.range, c(0, 10.5))
+
+ p <- ggplot_build(base + coord_cartesian(expand = c(top = FALSE, left = FALSE)))
+ pp <- p$layout$panel_params[[1]]
+ expect_equal(pp$x.range, c(0, 10.5))
+ expect_equal(pp$y.range, c(-0.5, 10))
+
+})
+