Scale palettes from theme (#5946)

* add palette theme elements

* set palettes

* expand options for numeric palettes

* backward compatibility for `options()` default scales

* use explicit scales in tests

* standard colour scales have `palette = NULL`

* document

* properly document this time

* misc fixes

* more palettes in theme

* use binned versions of discrete palettes for continuous linetype/shape

* Set default palettes to `NULL`

* tweak test to populate palettes

* try registered theme palettes

* document

* remove redundant call to `plot_theme()`

* simplify `fallback_palette()` args

* Put in shims for scales/#427

* Streamline `ScalesList$set_palettes()` method

* try to match first non-null aesthetic

* add news bullet

NEWS.md

@@ -215,6 +215,9 @@
 * Added `keep.zeroes` argument to `stat_bin()` (@teunbrand, #3449)
 * `coord_sf()` no longer errors when dealing with empty graticules (@teunbrand, #6052)
 * Added `theme_transparent()` with transparent backgrounds (@topepo).
+* New theme elements `palette.{aes}.discrete` and `palette.{aes}.continuous`. 
+  Theme palettes replace palettes in scales where `palette = NULL`, which is 
+  the new default in many scales (@teunbrand, #4696).
 
 # ggplot2 3.5.1
 

R/geom-text.R

@@ -95,7 +95,7 @@
 #' # Add aesthetic mappings
 #' p + geom_text(aes(colour = factor(cyl)))
 #' p + geom_text(aes(colour = factor(cyl))) +
-#'   scale_colour_discrete(l = 40)
+#'   scale_colour_hue(l = 40)
 #' p + geom_label(aes(fill = factor(cyl)), colour = "white", fontface = "bold")
 #'
 #' # Scale size of text, and change legend key glyph from a to point

R/plot-build.R

@@ -106,6 +106,7 @@ ggplot_build.ggplot <- function(plot) {
   # Train and map non-position scales and guides
   npscales <- scales$non_position_scales()
   if (npscales$n() > 0) {
+    npscales$set_palettes(plot$theme)
     lapply(data, npscales$train_df)
     plot$guides <- plot$guides$build(npscales, plot$layers, plot$labels, data, plot$theme)
     data <- lapply(data, npscales$map_df)

R/scale-.R

@@ -528,6 +528,7 @@ Scale <- ggproto("Scale", NULL,
     if (empty(df)) {
       return()
     }
+    self$palette <- self$palette %||% fallback_palette(self)
 
     aesthetics <- intersect(self$aesthetics, names(df))
     names(aesthetics) <- aesthetics

R/scale-alpha.R

@@ -31,8 +31,9 @@
 #'
 #' # Changing the title
 #' p + scale_alpha("cylinders")
-scale_alpha <- function(name = waiver(), ..., range = c(0.1, 1)) {
-  continuous_scale("alpha", name = name, palette = pal_rescale(range), ...)
+scale_alpha <- function(name = waiver(), ..., range = NULL) {
+  palette <- if (!is.null(range)) pal_rescale(range) else NULL
+  continuous_scale("alpha", name = name, palette = palette, ...)
 }
 
 #' @rdname scale_alpha
@@ -41,8 +42,9 @@ scale_alpha_continuous <- scale_alpha
 
 #' @rdname scale_alpha
 #' @export
-scale_alpha_binned <- function(name = waiver(), ..., range = c(0.1, 1)) {
-  binned_scale("alpha", name = name, palette = pal_rescale(range), ...)
+scale_alpha_binned <- function(name = waiver(), ..., range = NULL) {
+  palette <- if (!is.null(range)) pal_rescale(range) else NULL
+  binned_scale("alpha", name = name, palette = palette, ...)
 }
 
 #' @rdname scale_alpha
@@ -56,32 +58,33 @@ scale_alpha_discrete <- function(...) {
 
 #' @rdname scale_alpha
 #' @export
-scale_alpha_ordinal <- function(name = waiver(), ..., range = c(0.1, 1)) {
-  discrete_scale(
-    "alpha", name = name,
-    palette = function(n) seq(range[1], range[2], length.out = n),
-    ...
-  )
+scale_alpha_ordinal <- function(name = waiver(), ..., range = NULL) {
+  palette <- if (!is.null(range)) {
+    function(n) seq(range[1], range[2], length.out = n)
+  } else {
+    NULL
+  }
+  discrete_scale("alpha", name = name, palette = palette, ...)
 }
 
 #' @rdname scale_alpha
 #' @export
 #' @usage NULL
-scale_alpha_datetime <- function(name = waiver(), ..., range = c(0.1, 1)) {
+scale_alpha_datetime <- function(name = waiver(), ..., range = NULL) {
+  palette <- if (!is.null(range)) pal_rescale(range) else NULL
   datetime_scale(
     aesthetics = "alpha", transform = "time", name = name,
-    palette = pal_rescale(range),
-    ...
+    palette = palette, ...
   )
 }
 
 #' @rdname scale_alpha
 #' @export
 #' @usage NULL
-scale_alpha_date <- function(name = waiver(), ..., range = c(0.1, 1)){
+scale_alpha_date <- function(name = waiver(), ..., range = NULL){
+  palette <- if (!is.null(range)) pal_rescale(range) else NULL
   datetime_scale(
     aesthetics = "alpha", transform = "date", name = name,
-    palette = pal_rescale(range),
-    ...
+    palette = palette, ...
   )
 }

R/scale-colour.R

@@ -27,6 +27,7 @@
 #' you want to manually set the colors of a scale, consider using
 #' [scale_colour_gradient()] or [scale_colour_steps()].
 #'
+#' @inheritParams continuous_scale
 #' @param ... Additional parameters passed on to the scale type
 #' @param type One of the following:
 #'   * "gradient" (the default)
@@ -77,122 +78,81 @@
 #' v
 #' options(ggplot2.continuous.fill = tmp) # restore previous setting
 #' @export
-scale_colour_continuous <- function(...,
+scale_colour_continuous <- function(..., aesthetics = "colour",
+                                    guide = "colourbar", na.value = "grey50",
                                     type = getOption("ggplot2.continuous.colour")) {
-  type <- type %||% "gradient"
-  args <- list2(...)
-  args$call <- args$call %||% current_call()
 
-  if (is.function(type)) {
-    if (!any(c("...", "call") %in% fn_fmls_names(type))) {
-      args$call <- NULL
-    }
-    check_scale_type(exec(type, !!!args), "scale_colour_continuous", "colour")
-  } else if (identical(type, "gradient")) {
-    exec(scale_colour_gradient, !!!args)
-  } else if (identical(type, "viridis")) {
-    exec(scale_colour_viridis_c, !!!args)
-  } else {
-    cli::cli_abort(c(
-      "Unknown scale type: {.val {type}}",
-      "i" = "Use either {.val gradient} or {.val viridis}."
-    ))
+  if (!is.null(type)) {
+    scale <- scale_backward_compatibility(
+      ..., guide = guide, na.value = na.value, scale = type,
+      aesthetic = "colour", type = "continuous"
+    )
+    return(scale)
   }
+
+  continuous_scale(
+    aesthetics, palette = NULL, guide = guide, na.value = na.value,
+    ...
+  )
 }
 
 #' @rdname scale_colour_continuous
 #' @export
-scale_fill_continuous <- function(...,
+scale_fill_continuous <- function(..., aesthetics = "fill", guide = "colourbar",
+                                  na.value = "grey50",
                                   type = getOption("ggplot2.continuous.fill")) {
-  type <- type %||% "gradient"
-  args <- list2(...)
-  args$call <- args$call %||% current_call()
 
-  if (is.function(type)) {
-    if (!any(c("...", "call") %in% fn_fmls_names(type))) {
-      args$call <- NULL
-    }
-    check_scale_type(exec(type, !!!args), "scale_fill_continuous", "fill")
-  } else if (identical(type, "gradient")) {
-    exec(scale_fill_gradient, !!!args)
-  } else if (identical(type, "viridis")) {
-    exec(scale_fill_viridis_c, !!!args)
-  } else {
-    cli::cli_abort(c(
-      "Unknown scale type: {.val {type}}",
-      "i" = "Use either {.val gradient} or {.val viridis}."
-    ))
+  if (!is.null(type)) {
+    scale <- scale_backward_compatibility(
+      ..., guide = guide, na.value = na.value, scale = type,
+      aesthetic = "fill", type = "continuous"
+    )
+    return(scale)
   }
+
+  continuous_scale(
+    aesthetics, palette = NULL, guide = guide, na.value = na.value,
+    ...
+  )
 }
 
 #' @export
 #' @rdname scale_colour_continuous
-scale_colour_binned <- function(...,
+scale_colour_binned <- function(..., aesthetics = "colour", guide = "coloursteps",
+                                na.value = "grey50",
                                 type = getOption("ggplot2.binned.colour")) {
-  args <- list2(...)
-  args$call <- args$call %||% current_call()
-  if (is.function(type)) {
-    if (!any(c("...", "call") %in% fn_fmls_names(type))) {
-      args$call <- NULL
-    }
-    check_scale_type(exec(type, !!!args), "scale_colour_binned", "colour")
-  } else {
-    type_fallback <- getOption("ggplot2.continuous.colour", default = "gradient")
-    # don't use fallback from scale_colour_continuous() if it is
-    # a function, since that would change the type of the color
-    # scale from binned to continuous
-    if (is.function(type_fallback)) {
-      type_fallback <- "gradient"
-    }
-    type <- type %||% type_fallback
-
-    if (identical(type, "gradient")) {
-      exec(scale_colour_steps, !!!args)
-    } else if (identical(type, "viridis")) {
-      exec(scale_colour_viridis_b, !!!args)
-    } else {
-      cli::cli_abort(c(
-        "Unknown scale type: {.val {type}}",
-        "i" = "Use either {.val gradient} or {.val viridis}."
-      ))
-    }
+  if (!is.null(type)) {
+    scale <- scale_backward_compatibility(
+      ..., guide = guide, na.value = na.value, scale = type,
+      aesthetic = "colour", type = "binned"
+    )
+    return(scale)
   }
+
+  binned_scale(
+    aesthetics, palette = NULL, guide = guide, na.value = na.value,
+    ...
+  )
 }
 
 #' @export
 #' @rdname scale_colour_continuous
-scale_fill_binned <- function(...,
+scale_fill_binned <- function(..., aesthetics = "fill", guide = "coloursteps",
+                              na.value = "grey50",
                               type = getOption("ggplot2.binned.fill")) {
-  args <- list2(...)
-  args$call <- args$call %||% current_call()
-  if (is.function(type)) {
-    if (!any(c("...", "call") %in% fn_fmls_names(type))) {
-      args$call <- NULL
-    }
-    check_scale_type(exec(type, !!!args), "scale_fill_binned", "fill")
-  } else {
-    type_fallback <- getOption("ggplot2.continuous.fill", default = "gradient")
-    # don't use fallback from scale_colour_continuous() if it is
-    # a function, since that would change the type of the color
-    # scale from binned to continuous
-    if (is.function(type_fallback)) {
-      type_fallback <- "gradient"
-    }
-    type <- type %||% type_fallback
-
-    if (identical(type, "gradient")) {
-      exec(scale_fill_steps, !!!args)
-    } else if (identical(type, "viridis")) {
-      exec(scale_fill_viridis_b, !!!args)
-    } else {
-      cli::cli_abort(c(
-        "Unknown scale type: {.val {type}}",
-        "i" = "Use either {.val gradient} or {.val viridis}."
-      ))
-    }
+  if (!is.null(type)) {
+    scale <- scale_backward_compatibility(
+      ..., guide = guide, na.value = na.value, scale = type,
+      aesthetic = "fill", type = "binned"
+    )
+    return(scale)
   }
-}
 
+  binned_scale(
+    aesthetics, palette = NULL, guide = guide, na.value = na.value,
+    ...
+  )
+}
 
 # helper function to make sure that the provided scale is of the correct
 # type (i.e., is continuous and works with the provided aesthetic)
@@ -222,3 +182,73 @@ check_scale_type <- function(scale, name, aesthetic, scale_is_discrete = FALSE,
 
   scale
 }
+
+# helper function for backwards compatibility through setting defaults
+# scales through `options()` instead of `theme()`.
+scale_backward_compatibility <- function(..., scale, aesthetic, type) {
+  aesthetic <- standardise_aes_names(aesthetic[1])
+
+  args <- list2(...)
+  args$call <- args$call %||% caller_call() %||% current_call()
+
+  if (type == "binned") {
+    fallback <- getOption(
+      paste("ggplot2", type, aesthetic, sep = "."),
+      default = "gradient"
+    )
+    if (is.function(fallback)) {
+      fallback <- "gradient"
+    }
+    scale <- scale %||% fallback
+  }
+
+  if (is_bare_string(scale)) {
+    if (scale == "continuous") {
+      scale <- "gradient"
+    }
+    if (scale == "discrete") {
+      scale <- "hue"
+    }
+    if (scale == "viridis") {
+      scale <- switch(
+        type, discrete = "viridis_d", binned = "viridis_b", "viridis_c"
+      )
+    }
+
+    candidates <- paste("scale", aesthetic, scale, sep = "_")
+    for (candi in candidates) {
+      f <- find_global(candi, env = caller_env(), mode = "function")
+      if (!is.null(f)) {
+        scale <- f
+        break
+      }
+    }
+  }
+
+  if (!is.function(scale) && type == "discrete") {
+    args$type <- scale
+    scale <- switch(
+      aesthetic,
+      colour = scale_colour_qualitative,
+      fill   = scale_fill_qualitative
+    )
+  }
+
+  if (is.function(scale)) {
+    if (!any(c("...", "call") %in% fn_fmls_names(scale))) {
+      args$call <- NULL
+    }
+    if (!"..." %in% fn_fmls_names(scale)) {
+      args <- args[intersect(names(args), fn_fmls_names(scale))]
+    }
+    scale <- check_scale_type(
+      exec(scale, !!!args),
+      paste("scale", aesthetic, type, sep = "_"),
+      aesthetic,
+      scale_is_discrete = type == "discrete"
+    )
+    return(scale)
+  }
+
+  cli::cli_abort("Unknown scale type: {.val {scale}}")
+}