theme_get: Get, set, and modify the active theme

In ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

Get, set, and modify the active theme

Description

The current/active theme (see theme()) is automatically applied to every plot you draw. Use theme_get() to get the current theme, and theme_set() to completely override it. theme_update() and theme_replace() are shorthands for changing individual elements.

Usage

theme_get()

theme_set(new)

theme_update(...)

theme_replace(...)

e1 %+replace% e2

Arguments

new	new theme (a list of theme elements)
...	named list of theme settings
e1, e2	Theme and element to combine

Value

theme_set(), theme_update(), and theme_replace() invisibly return the previous theme so you can easily save it, then later restore it.

Adding on to a theme

+ and ⁠%+replace%⁠ can be used to modify elements in themes.

+ updates the elements of e1 that differ from elements specified (not NULL) in e2. Thus this operator can be used to incrementally add or modify attributes of a ggplot theme.

In contrast, ⁠%+replace%⁠ replaces the entire element; any element of a theme not specified in e2 will not be present in the resulting theme (i.e. NULL). Thus this operator can be used to overwrite an entire theme.

theme_update() uses the + operator, so that any unspecified values in the theme element will default to the values they are set in the theme. theme_replace() uses ⁠%+replace%⁠ to completely replace the element, so any unspecified values will overwrite the current value in the theme with NULL.

In summary, the main differences between theme_set(), theme_update(), and theme_replace() are:

• theme_set() completely overrides the current theme.

• theme_update() modifies a particular element of the current theme using the + operator.

• theme_replace() modifies a particular element of the current theme using the ⁠%+replace%⁠ operator.

See Also

+.gg()

Examples

p <- ggplot(mtcars, aes(mpg, wt)) +
  geom_point()
p

# Use theme_set() to completely override the current theme.
# theme_update() and theme_replace() are similar except they
# apply directly to the current/active theme.
# theme_update() modifies a particular element of the current theme.
# Here we have the old theme so we can later restore it.
# Note that the theme is applied when the plot is drawn, not
# when it is created.
old <- theme_set(theme_bw())
p

theme_set(old)
theme_update(panel.grid.minor = element_line(colour = "red"))
p

theme_set(old)
theme_replace(panel.grid.minor = element_line(colour = "red"))
p

theme_set(old)
p


# Modifying theme objects -----------------------------------------
# You can use + and %+replace% to modify a theme object.
# They differ in how they deal with missing arguments in
# the theme elements.

add_el <- theme_grey() +
  theme(text = element_text(family = "Times"))
add_el$text

rep_el <- theme_grey() %+replace%
  theme(text = element_text(family = "Times"))
rep_el$text

ggplot2 documentation built on June 22, 2024, 11:35 a.m.