scale_gshape_manual: Scale for 'gshape' aesthetic

In ggalign: A 'ggplot2' Extension for Consistent Axis Alignment

Scale for gshape aesthetic

Description

geom_gshape depends on the new aesthetics gshape (shape with grid functions), which should always be provided with scale_gshape_manual(), in which, we can provide a list of grobs or functions that define how each value should be drawn. Any ggplot2 aesthetics can be used as the arguments.

Usage

scale_gshape_manual(..., values, breaks = waiver(), na.value = NA)

Arguments

...	Arguments passed on to ggplot2::discrete_scale name The name of the scale. Used as the axis or legend title. If waiver(), the default, the name of the scale is taken from the first mapping used for that aesthetic. If NULL, the legend title will be omitted. labels One of: NULL for no labels waiver() for the default labels computed by the transformation object A character vector giving labels (must be same length as breaks) An expression vector (must be the same length as breaks). See ?plotmath for details. A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation. limits One of: NULL to use the default scale values A character vector that defines possible values of the scale and their order A function that accepts the existing (automatic) values and returns new ones. Also accepts rlang lambda function notation. na.translate Unlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE. drop Should unused factor levels be omitted from the scale? The default, TRUE, uses the levels that appear in the data; FALSE includes the levels in the factor. Please note that to display every level in a legend, the layer should use show.legend = TRUE. guide A function used to create a guide or its name. See guides() for more information. call The call used to construct the scale for reporting messages. super The super class to use for the constructed scale
values	A list of grobs or functions (including purrr-like lambda syntax) that define how each cell's grob (graphical object) should be drawn.
breaks	One of: NULL for no breaks waiver() for the default breaks (the scale limits) A character vector of breaks A function that takes the limits as input and returns breaks as output
na.value	The aesthetic value to use for missing (NA) values

Life cycle

We're unsure whether this function is truly necessary, which is why it is marked as questioning. So far, we've found that geom_subrect() and geom_subtile() handle most use cases effectively.

Aesthetics

geom_gshape() understands the following aesthetics (required aesthetics are in bold):

• x

• y

• gshape

• alpha

• colour

• fill

• group

• linetype

• linewidth

• shape

• size

• stroke

Learn more about setting these aesthetics in vignette("ggplot2-specs", package = "ggplot2").

Examples

library(grid)
ggplot(data.frame(value = letters[seq_len(5)], y = seq_len(5))) +
    geom_gshape(aes(x = 1, y = y, gshape = value, fill = value)) +
    scale_gshape_manual(values = list(
        a = function(x, y, width, height, fill) {
            rectGrob(x, y,
                width = width, height = height,
                gp = gpar(fill = fill),
                default.units = "native"
            )
        },
        b = function(x, y, width, height, fill) {
            rectGrob(x, y,
                width = width, height = height,
                gp = gpar(fill = fill),
                default.units = "native"
            )
        },
        c = function(x, y, width, height, fill) {
            rectGrob(x, y,
                width = width, height = height,
                gp = gpar(fill = fill),
                default.units = "native"
            )
        },
        d = function(x, y, width, height, shape) {
            gList(
                pointsGrob(x, y, pch = shape),
                # To ensure the rectangle color is shown in the legends, you
                # must explicitly provide a color argument and include it in
                # the `gpar()` of the graphical object
                rectGrob(x, y, width, height,
                    gp = gpar(col = "black", fill = NA)
                )
            )
        },
        e = function(xmin, xmax, ymin, ymax) {
            segmentsGrob(
                xmin, ymin,
                xmax, ymax,
                gp = gpar(lwd = 2)
            )
        }
    )) +
    scale_fill_brewer(palette = "Dark2") +
    theme_void()

ggalign documentation built on June 8, 2025, 11:25 a.m.