Adds tags to facets

Adds tags to facets

tag_facets(
  tag = c("panel", "rc", "cr"),
  position = "tl",
  tag_levels = c("a", "1"),
  tag_pool = NULL,
  tag_prefix = "",
  tag_suffix = ")",
  tag_sep = "."
)

Arguments

tag	Character indicating the element to tag. Possible values are "panel": each single panels is individually tag. "rc": facets are tagged by row and then column. "cr": factes are tagged by columns and then row.
position	Character indicating the position of the tag. Options are "tl" (top-left), "tr" (top-right), "br" (bottom-right) and "bl" (bottom-left). Alternatively, for finer control, it can be a list of elements "x", "u", "hjust" and "vjust" that define the position of the tag within each panel.
tag_levels	A character vector defining the enumeration format to use at each level. Possible values are 'a' for lowercase letters, 'A' for uppercase letters, '1' for numbers, 'i' for lowercase Roman numerals, and 'I' for uppercase Roman numerals.
tag_pool	An optional character vector of user-defined "pool" of tags. If not NULL, it will be used instead of tag_levels. Should be at least as long as the total number of panels.
tag_prefix	Strings that should appear before or after the tag.
tag_suffix	Strings that should appear before or after the tag.
tag_sep	A separator between different tag levels

Details

Tags inherit aesthetic properties (size, font, colour, etc...) from strip.text and strip.background defined by ggplot2::theme(). For fine-grained detail, these can be overriden by setting tagger.panel.tag.text and tagger.panel.tag.background.

Examples

library(ggplot2)
# Base plot
g <- ggplot(mtcars, aes(hp, mpg)) +
  geom_point() +
  facet_grid(cyl ~ vs)

g + tag_facets()
g + tag_facets("rc")
g + tag_facets(position = "br")
g + tag_facets("rc", tag_levels  = c("A", "I"))

# You can get finer control over position.
g + tag_facets(position = list(x = 0.5, y = 0.5, hjust = 0, vjust = 0))

g + tag_facets(tag_pool = c("one", "two", "three", "four", "five", "six"), tag_suffix = "")
# Thanks to theme inheritance, tags should look aceptable
# out of the box in any theme.
g + tag_facets() +
   theme_dark()

# But you can control their appearance and create your own atrocities
g + tag_facets() +
   theme_dark() +
   theme(tagger.panel.tag.text = element_text(color = "red", size = 16),
         tagger.panel.tag.background = element_rect(fill = "purple"))