Introduction to ‘ggfittext’

David Wilkins

2019-07-18

Fitting text inside a box

Sometimes you want to draw some text in a ggplot2 plot so that it fits inside a defined area. It’s possible to achieve this by manually fiddling with the font size, but this is both tedious and un-reproducible. ggfittext provides a geom called geom_fit_text() that automatically resizes text to fit inside a box. It works like this:

library(ggfittext)
library(ggplot2)
ggplot(animals, aes(x = type, y = flies, label = animal)) +
  geom_tile(fill = "white", colour = "black") +
  geom_fit_text()

As with geom_text(), the position of the text is set by the x and y aesthetics. geom_fit_text() automatically infers the width and height of the box in which the text is allowed to fit, and shrinks down any text that is too big.

Reflowing text

Another way to make the text fit in the box is by reflowing it; that is, wrapping it over multiple lines. With the reflow = TRUE argument, geom_fit_text() will reflow the text before (if still necessary) shrinking it:

ggplot(animals, aes(x = type, y = flies, label = animal)) +
  geom_tile(fill = "white", colour = "black") +
  geom_fit_text(reflow = TRUE)

Growing text

If you want the text to be as large as possible, the argument grow = TRUE will increase the text size to the maximum that will fit in the box. This works well in conjunction with reflow:

ggplot(animals, aes(x = type, y = flies, fill = mass, label = animal)) +
  geom_tile(fill = "white", colour = "black") +
  geom_fit_text(reflow = TRUE, grow = TRUE)

Placing text

By default, text is placed in the centre of the box. However, you can place it in a corner or on a side of the box with the place argument, which takes values “top”, “topright”, “right”, “bottomright”, “bottom”, “bottomleft” and so on:

ggplot(animals, aes(x = type, y = flies, label = animal)) +
  geom_tile(fill = "white", colour = "black") +
  geom_fit_text(place = "topleft", reflow = TRUE)

Bar plots

ggfittext provides a convenience function geom_bar_text() for labelling bars in bar plots:

ggplot(altitudes, aes(x = craft, y = altitude, label = altitude)) +
  geom_col() +
  geom_bar_text()

geom_bar_text() also works with stacked bar plots (position = "stack"):

ggplot(coffees, aes(x = coffee, y = proportion, label = ingredient,
                    fill = ingredient)) +
  geom_col(position = "stack") +
  geom_bar_text(position = "stack", grow = TRUE, reflow = TRUE)

And with dodged bar plots, and coord_flip():

ggplot(coffees, aes(x = coffee, y = proportion, label = ingredient,
                    fill = ingredient)) +
  geom_col(position = "dodge") +
  geom_bar_text(position = "dodge", grow = TRUE, reflow = TRUE, 
                place = "left") +
  coord_flip()

Specifying the box coordinates

If you want to manually set the edges of the box (instead of having them inferred from x and y), you can use xmin & xmax and/or ymin & ymax:

ggplot(presidential, aes(ymin = start, ymax = end, x = party, label = name)) +
  geom_fit_text(grow = TRUE) +
  geom_errorbar(alpha = 0.5)

Alternatively, you can set the width and/or height with the width and/or height arguments, which should be grid::unit() objects. The horizontal and/or vertical centre of the box will be defined by x and/or y.

Other useful arguments

All arguments to geom_fit_text() can also be used with geom_bar_text().

ggplot(animals, aes(x = type, y = flies, fill = mass, label = animal)) +
  geom_tile() +
  geom_fit_text(reflow = TRUE, grow = TRUE, contrast = TRUE)