Make the background of a graph different colours in different regions

Question

I'm making a straightforward barchart in R using the ggplot2 package. Rather than the grey default I'd like to divide the background into five regions, each a different (but similarly understated) colour. How do I do this?

More specifically, I'd like the five coloured regions to run from 0-25, 25-45, 45-65, 65-85 and 85-100 where the colours represent worse-than-bronze, bronze, silver, gold and platinum respectively. Suggestions for a colour scheme very welcome too.

Answer 1

Here's an example to get you started:

#Fake data dat <- data.frame(x = 1:100, y = cumsum(rnorm(100))) #Breaks for background rectangles rects <- data.frame(xstart = seq(0,80,20), xend = seq(20,100,20), col = letters[1:5])   #As Baptiste points out, the order of the geom's matters, so putting your data as last will  #make sure that it is plotted "on top" of the background rectangles. Updated code, but #did not update the JPEG...I think you'll get the point.  ggplot() +    geom_rect(data = rects, aes(xmin = xstart, xmax = xend, ymin = -Inf, ymax = Inf, fill = col), alpha = 0.4) +   geom_line(data = dat, aes(x,y)) 

Answer 2

I wanted to move the line⎯or the bars of the histogram⎯to the foreground, as suggested by baptiste above and fix the background with + theme(panel.background = element_rect(), panel.grid.major = element_line( colour = "white") ), unfortunately I could only do it by sending the geom_bar twice, hopefully someone can improve the code and make the answer complete.

background <- data.frame(lower = seq( 0  , 3  , 1.5 ),                           upper = seq( 1.5, 4.5, 1.5 ),                          col = letters[1:3]) ggplot() +      geom_bar( data = mtcars , aes( factor(cyl) ) ) +      geom_rect( data = background ,                mapping = aes( xmin = lower ,                              xmax = upper ,                             ymin = 0 ,                             ymax = 14 ,                             fill = col ) ,               alpha = .5 ) +      geom_bar(data = mtcars,              aes(factor(cyl))) +              theme(panel.background = element_rect(),                    panel.grid.major = element_line( colour = "white")) 

Produces this,

Take a look at this site for colour scheme suggestions.