Strip labels: labeller

Mix.install([
  {:giggly, path: Path.join(__DIR__, "..")},
  {:kino, "~> 0.19"}
  ])

About this notebook

This notebook follows the examples on ggplot2's reference page for labeller(), in the order the page gives them. Each example shows ggplot2's code first and then Giggly's. An example Giggly cannot draw yet keeps its ggplot2 code and names what it is waiting for, so the page is also a list of what remains.

A labeller writes the labels in a facet's strips from the values of its columns. labeller() builds one from a labeller for each column, or one for all the rows' strips and one for all the columns', and a default for the rest; each may be a labeller function, a function on strings, or a lookup table of the labels to show in place of the values. The result goes to the labeller argument of facet_grid() or facet_wrap(). Giggly has none of it yet: neither Giggly.Plot.facet_grid/2 nor Giggly.Plot.facet_wrap/3 takes a labeller option.

A labeller for each column

p1 <- ggplot(mtcars, aes(x = mpg, y = wt)) + geom_point()

# You can assign different labellers to variables:
p1 + facet_grid(
  vs + am ~ gear,
  labeller = labeller(vs = label_both, am = label_value)
)

Not in Giggly yet: facet_grid()'s labeller option, labeller(), label_both() and label_value().

A labeller for the rows and one for the columns

# Or whole margins:
p1 + facet_grid(
  vs + am ~ gear,
  labeller = labeller(.rows = label_both, .cols = label_value)
)

Not in Giggly yet: facet_grid()'s labeller option, labeller(), label_both() and label_value().

A function on strings

capitalize() upper-cases the first letter of each label.

# You can supply functions operating on strings:
capitalize <- function(string) {
  substr(string, 1, 1) <- toupper(substr(string, 1, 1))
  string
}
p2 <- ggplot(msleep, aes(x = sleep_total, y = awake)) + geom_point()
p2 + facet_grid(vore ~ conservation, labeller = labeller(vore = capitalize))

Not in Giggly yet: the msleep dataset, facet_grid()'s labeller option and labeller().

A lookup table

The named vector gives each conservation code its long form, and capitalize() labels the other strips.

# Or use character vectors as lookup tables:
conservation_status <- c(
  cd = "Conservation Dependent",
  en = "Endangered",
  lc = "Least concern",
  nt = "Near Threatened",
  vu = "Vulnerable",
  domesticated = "Domesticated"
)
## Source: http://en.wikipedia.org/wiki/Wikipedia:Conservation_status

p2 + facet_grid(vore ~ conservation, labeller = labeller(
  .default = capitalize,
  conservation = conservation_status
))

Not in Giggly yet: the msleep dataset, facet_grid()'s labeller option and labeller().

Wrapping long labels

# In the following example, we rename the levels to the long form,
# then apply a wrap labeller to the columns to prevent cropped text
idx <- match(msleep$conservation, names(conservation_status))
msleep$conservation2 <- conservation_status[idx]

p3 <- ggplot(msleep, aes(x = sleep_total, y = awake)) + geom_point()
p3 +
  facet_grid(vore ~ conservation2,
    labeller = labeller(conservation2 = label_wrap_gen(10))
  )

Not in Giggly yet: the msleep dataset, facet_grid()'s labeller option, labeller(), and label_wrap_gen(), which wraps each label at 10 characters.

One labeller for several plots

# labeller() is especially useful to act as a global labeller. You
# can set it up once and use it on a range of different plots with
# different facet specifications.

global_labeller <- labeller(
  vore = capitalize,
  conservation = conservation_status,
  conservation2 = label_wrap_gen(10),
  .default = label_both
)

p2 + facet_grid(vore ~ conservation, labeller = global_labeller)
p3 + facet_wrap(~conservation2, labeller = global_labeller)

Not in Giggly yet: the msleep dataset, labeller(), label_wrap_gen(), label_both(), facet_grid()'s labeller option, and facet_wrap()'s labeller option.