Italics in ggplot facet labels

italic_facets.R

# Say I have some short-hand labels like "Ec/q",
# which actually stand for "E. coli & quinolones",
# but I want "E. coli" to be in italics

library(tidyverse)

n <- 100

tibble(
  x = rnorm(n),
  y = rnorm(n),
  short_label = sample(c("Ec/q", "Sp/m"), size = n, replace = TRUE),
  long_label = recode(
    short_label,
    "Ec/q" = "italic('E. coli')~'& quinolones'",
    "Sp/m" = "italic('S. pneumoniae')~'& quinolones'"
  )
) %>%
  ggplot(aes(x, y)) +
  geom_point() +
  facet_wrap(~ long_label, labeller = label_parsed)

I'm surprised you found this old gist of mine!

I fixed that typo you noted and updated the syntax for more recent tidyverse versions. See below for how I would deal with your case. The key is learning about R expressions. This thread has some examples of different ways to do expressions. I like writing them as strings and having ggplot do all the parsing.

Tibble is just a way to make a data frame.

library(tidyverse)

data <- tibble(
  species = c("shigella", "ttr"),
  label = c("'EIEC/' * italic('Shigella') ~ 'spp.'", "italic('Salmonella') ~ 'species'"),
  x = c(1, 2),
  y = c(3, 4)
)

data %>%
  ggplot(aes(x, y)) +
  facet_wrap(vars(label), labeller = label_parsed) +
  geom_point()