R ggplot2 theme_get 获取、设置和修改活动主题

theme_get()

theme_set(new)

theme_update(...)

theme_replace(...)

e1 %+replace% e2

+.gg()

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
#> List of 11
#>  $ family       : chr "Times"
#>  $ face         : chr "plain"
#>  $ colour       : chr "black"
#>  $ size         : num 11
#>  $ hjust        : num 0.5
#>  $ vjust        : num 0.5
#>  $ angle        : num 0
#>  $ lineheight   : num 0.9
#>  $ margin       : 'margin' num [1:4] 0points 0points 0points 0points
#>   ..- attr(*, "unit")= int 8
#>  $ debug        : logi FALSE
#>  $ inherit.blank: logi FALSE
#>  - attr(*, "class")= chr [1:2] "element_text" "element"

rep_el <- theme_grey() %+replace%
  theme(text = element_text(family = "Times"))
rep_el$text
#> List of 11
#>  $ family       : chr "Times"
#>  $ face         : NULL
#>  $ colour       : NULL
#>  $ size         : NULL
#>  $ hjust        : NULL
#>  $ vjust        : NULL
#>  $ angle        : NULL
#>  $ lineheight   : NULL
#>  $ margin       : NULL
#>  $ debug        : NULL
#>  $ inherit.blank: logi FALSE
#>  - attr(*, "class")= chr [1:2] "element_text" "element"