ggplot2 (version 3.4.0)

theme_get: 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

Value

theme_set(), theme_update(), and theme_replace()

invisibly return the previous theme so you can easily save it, then later restore it.

Arguments

new

new theme (a list of theme elements)

...

named list of theme settings

e1, e2

Theme and element to combine

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

Run this code
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

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