Create a custom theme that can inherit theme parameters-CodePudding

I wish to create a custom theme function, which can inherit all the arguments from theme.

So far, I have something like:

my_theme <- function(...){
  theme(axis.title = element_text(colour = "red"))
}

If I want to change the plot background for example, I currently need to do:

ggplot(iris,
       aes(x = Species, y = Sepal.Length))  
  geom_boxplot()  
  my_theme()  
  theme(panel.background = element_rect(fill = "blue",
                                        colour = "green"))

While I wish I could do:

ggplot(iris,
       aes(x = Species, y = Sepal.Length))  
  geom_boxplot()  
  my_theme(panel.background = element_rect(fill = "blue",
                                        colour = "green"))

I guess I have to initialize all the theme's arguments inside the custom function, but is there another work around? Thanks!

CodePudding user response：

You could just pass on the ellipses to theme()?

library(ggplot2)

my_theme <- function(..., axis.title = NULL) {
  axis.title <- if (is.null(axis.title)) {
    element_text(colour = "red") 
  } else {
    axis.title
  } 
  theme(axis.title = axis.title, ...)
}

# Alternatively
my_theme <- function(..., axis.title = element_text(colour = "red")) {
  theme(axis.title = axis.title, ...)
}

ggplot(iris,
       aes(x = Species, y = Sepal.Length))  
  geom_boxplot()  
  my_theme(panel.background = element_rect(fill = "blue",
                                           colour = "green"))

^{Created on 2022-02-09 by the reprex package (v2.0.1)}

Another option if you're writing scripts/notebooks for yourself with no intention to package up your code is to just use theme_set() at the beginning, which propagates to all subsequent plots. This is how most of my scripts start.

library(ggplot2)

theme_set(theme_get()   theme(axis.title = element_text(colour = "red")))

ggplot(iris,
       aes(x = Species, y = Sepal.Length))  
  geom_boxplot()  
  theme(panel.background = element_rect(fill = "blue",
                                        colour = "green"))