label_glue: Label facets with a string template.

In rensa/stickylabeller: Quickly Number Ggplot2 Facets

Label facets with a string template.

Description

Returns a labeller function that you can give to the labeller argument of a ⁠facet_*⁠ function.

Usage

label_glue(row_template, col_template, summary_data = NULL, ...)

Arguments

row_template	A string to be used as the template by glue::glue_data().
col_template	A string to be used as the template by glue::glue_data().
summary_data	A data frame of additional variables to reference in the templates. Must also include the facet grouping variables.
...	Other arguments to be passed to glue::glue_data()

Details

If you're using label_glue() with ggplot2::facet_wrap() or you're individually supplying labellers to each variable, you only need one string template: row_template.

If you're using it with ggplot2::facet_grid(), you need to supply two templates: one for the rows (row_template) and one for the columns (col_template).

If you're using the labeller with ggplot2::facet_wrap(), you can also use these variables in the templates:

• .n to add numbers to each facet;

• .l or .L to add lower- or uppercase letters

• .r or .R to add lower- or uppercase roman numerals.

Value

A labelling function that you can give to the labeller argument of the facetting function.

Examples

library(ggplot2)
library(stickylabeller)

# wrap facet columns in braces to refer to their values in the labels
p1 <- ggplot(iris, aes(x = Sepal.Length, y = Petal.Length)) + geom_point()
p1 + facet_wrap(
  ~  Species,
  labeller = label_glue("Sepal and petal lengths in {Species} plants"))

# distinguish panels with .n (numbers), .l (lowercase), .L (uppercase),
# .r or .R (lower- or uppercase roman) if you're using facet_wrap
p1 + facet_wrap(
  ~  Species,
  labeller = label_glue("({.n}) {Species}"))

# you can also use label_glue with facet_grid
p2 <- ggplot(mtcars, aes(x = disp, y = mpg)) + geom_point()
p2 + facet_grid(
  gear ~ cyl,
  labeller = label_glue(
    row_template = "{gear} gears",
    col_template = "{cyl} cylinders"))

# you can add summary statistics in a couple of ways. the easiest (in terms
# of plot code) is to join a summary back into the original data and to add
# the new columns in the facet spec
library(dplyr)
cyl_stats <- mtcars %>%
  group_by(cyl) %>%
  summarise(cyl_n = n(), cyl_meanmpg = sprintf("%#.2f", mean(mpg)))
mtcars_joined <- mtcars %>% inner_join(cyl_stats)

p3 <- ggplot(mtcars_joined, aes(x = disp, y = mpg)) + geom_point()
p3 + facet_wrap(
  ~ cyl + cyl_n + cyl_meanmpg,
  labeller = label_glue(
    "({.l}) {cyl} cylinders\n(n = {cyl_n}, mean = {cyl_meanmpg})"))

rensa/stickylabeller documentation built on June 12, 2025, 10:44 p.m.