Axis guide with brackets

Source: R/guide_prism_bracket.R

This guide turns the axis into brackets drawn around each axis label.

guide_prism_bracket(
  title = waiver(),
  check.overlap = FALSE,
  angle = NULL,
  n.dodge = 1,
  order = 0,
  position = waiver(),
  width = NULL,
  outside = TRUE
)

Arguments

title

A character string or expression indicating a title of guide. If NULL, the title is not shown. By default (waiver()), the name of the scale object or the name specified in labs() is used for the title.

check.overlap

silently remove overlapping labels, (recursively) prioritizing the first, last, and middle labels.

angle

Compared to setting the angle in theme() / element_text(), this also uses some heuristics to automatically pick the hjust and vjust that you probably want. Can be one of the following:

  • NULL to take the angles and hjust/vjust directly from the theme.

  • waiver() to allow reasonable defaults in special cases.

  • A number representing the text angle in degrees.

n.dodge

The number of rows (for vertical axes) or columns (for horizontal axes) that should be used to render the labels. This is useful for displaying labels that would otherwise overlap.

order

A positive integer of length 1 that specifies the order of this guide among multiple guides. This controls in which order guides are merged if there are multiple guides for the same position. If 0 (default), the order is determined by a secret algorithm.

position

Where this guide should be drawn: one of top, bottom, left, or right.

width

numeric. Controls the width of the bracket. Try values between 0 and 1.

outside

logical. Default is TRUE and brackets point outwards. If FALSE the bracket crossbar is moved so the ticks appear to point inwards towards the plotting area.

Value

Returns a prism_bracket guide class object.

Details

The number of brackets can be adjusted using the breaks argument in scale_(x|y)_continuous() or scale_(x|y)_discrete().

Examples

library(ggplot2)

## base plot
base <- ggplot(mpg, aes(x = as.factor(cyl), y = hwy)) +
  geom_jitter(width = 0.2) +
  theme(axis.line = element_line(colour = "black"))

## use brackets on x axis
# if not specified, the width of the brackets is guessed
base + scale_x_discrete(guide = "prism_bracket")


# you can add brackets using the guide function as well
base + guides(x = "prism_bracket")


## works with coord_flip
base + scale_x_discrete(guide = "prism_bracket") +
  coord_flip()


## adjust bracket width
base + scale_x_discrete(guide = guide_prism_bracket(width = 0.12))


## make brackets point inward
base + scale_x_discrete(guide = guide_prism_bracket(width = 0.12, outside = FALSE))


## change colour with the usual axis.line, axis.ticks, axis.text elements
base + scale_x_discrete(guide = guide_prism_bracket(width = 0.12, outside = FALSE)) +
  theme(axis.line.x = element_line(colour = "red"),
        axis.ticks.x = element_line(colour = "blue"),
        axis.text.x = element_text(colour = "green"))