Add ticks as ggplot annotation

This is an annotation function to add tick marks (major, minor, or both) to a ggplot. Clipping must be turned off if the ticks are to appear outside the plotting area, for example with: coord_cartesian(clip = "off").

annotation_ticks(
  sides = "b",
  type = "both",
  outside = FALSE,
  tick.length = unit(4.8, "pt"),
  minor.length = unit(2.4, "pt"),
  linewidth = 0.6,
  colour = "black",
  color = NULL,
  linetype = 1,
  lineend = "butt",
  alpha = 1,
  data = data.frame(x = NA)
)

Source

The code is a slightly modified version of the answer to this Stack Overflow question, which is itself a refactored version of this annotation_ticks() function.

Arguments

sides

string. Indicates which sides of the plot should ticks appear. Can be any of "trbl", for top, right, bottom, left.

type

string. Types of ticks that appear. One of "major", "minor", or "both". Control number of ticks by controlling the breaks and minor_breaks arguments in the various ggplot2 scale_(x|y)_ functions.

outside

logical. Should the ticks point outside of the plotting area? If TRUE clipping must be turned off.

tick.length

a unit object specifying the length of major ticks.

minor.length

a unit object specifying the length of minor ticks.

linewidth

numeric. Linewidth of ticks.

colour, color

string. Colour of ticks.

linetype

string or numeric. Linetype of tick marks.

lineend

string. Lineend of ticks. One of "square" (default), "butt", or "round".

alpha

numeric. Transparency of ticks.

data

data.frame. Use this argument to control the appearance of ticks on different facets. Pass a data.frame containing the levels from the faceting variable you want to annotate specifically. See here for an example.

Value

Returns a layer ggproto object with geom = GeomTicks.

Examples

## Generally it is better to use the guide_prism_minor function.
## However annotation_ticks is useful in a few specific situations.
library(ggplot2)

## easily put ticks without labels around a plot with a border
ggplot(mtcars, aes(x = mpg, y = disp)) +
  geom_point() +
  theme_prism(border = TRUE) +
  coord_cartesian(clip = "off") +
  annotation_ticks(sides = "tr", type = "major", outside = TRUE) +
  theme(plot.margin = unit(c(4, 4, 4, 4), "mm"))


# the same but with minor ticks as well
ggplot(mtcars, aes(x = mpg, y = disp)) +
  geom_point() +
  scale_x_continuous(guide = "prism_minor") +
  scale_y_continuous(guide = "prism_minor") +
  theme_prism(border = TRUE) +
  coord_cartesian(clip = "off") +
  annotation_ticks(sides = "tr", type = "both", outside = TRUE) +
  theme(plot.margin = unit(c(4, 4, 4, 4), "mm"))
#> Warning: The S3 guide system was deprecated in ggplot2 3.5.0.
#> ℹ It has been replaced by a ggproto system that can be extended.


# you can adjust the appearance of annotation_ticks
ggplot(mtcars, aes(x = mpg, y = disp)) +
  geom_point() +
  theme_prism(border = TRUE) +
  coord_cartesian(clip = "off") +
  annotation_ticks(
    sides = "tr",
    type = "major",
    outside = TRUE,
    tick.length = unit(10, "pt"),
    colour = "red",
    linewidth = 2,
    linetype = "dashed",
    lineend = "round"
  ) +
  theme(plot.margin = unit(c(4, 4, 4, 4), "mm"))


## Unfortunately, due to the way they work, secondary axes don't always play
## well with the minor tick axes guides in this package.
## So we can use annotation_ticks instead.
sample.data <- data.frame(
  day = as.Date("2019-01-01") + 0:99,
  temperature = runif(100) + seq(1, 100)^2.5 / 10000,
  price = runif(100) + seq(100, 1)^1.5 / 10
)

# sample graph with secondary axis
ggplot(sample.data, aes(x = day)) +
  geom_line(aes(y = temperature), colour = "magenta") +
  geom_line(aes(y = price / 10), colour = "blue") +
  scale_y_continuous(sec.axis = sec_axis(~. * 10, name = "price")) +
  theme_prism(border = TRUE) +
  coord_cartesian(clip = "off")


# guide_prism_minor only works with the main axis in this case
ggplot(sample.data, aes(x = day)) +
  geom_line(aes(y = temperature), colour = "magenta") +
  geom_line(aes(y = price / 10), colour = "blue") +
  scale_y_continuous(
    sec.axis = sec_axis(~. * 10, name = "price"),
    guide = "prism_minor"
  ) +
  theme_prism(border = TRUE) +
  coord_cartesian(clip = "off")


# we use annotation_ticks to draw the minor ticks on the secondary axis
ggplot(sample.data, aes(x = day)) +
  geom_line(aes(y = temperature), colour = "magenta") +
  geom_line(aes(y = price / 10), colour = "blue") +
  scale_y_continuous(
    sec.axis = sec_axis(~. * 10, name = "price"),
    guide = "prism_minor"
  ) +
  theme_prism(border = TRUE) +
  coord_cartesian(clip = "off") +
  annotation_ticks(sides = "r", type = "minor", outside = TRUE)