R: bar plot with two groups, of which one is stacked

Question

I've encountered a small problem when creating a bar plot in R. There are 3 variables:

a <- c(3,3,2,1,0)
b <- c(3,2,2,2,2)
c <- 0:4

The bar plot should be grouped by 'a' and 'c', and 'b' should be stacked on top of 'a'. Doing the grouping and stacking seperately is straightforward:

barplot(rbind(a,c), beside=TRUE)
barplot(rbind(a,b), beside=FALSE)

How can you do both at once in one graph?

Maybe this will help: http://stackoverflow.com/questions/1801064/how-to-separate-two-plots-in-r — Mark Miller, Aug 06 '13 at 13:16

Thomas · Accepted Answer · 2014-03-26T20:24:43.417

10

Doing this requires thinking about how barplot draws stacked bars. Basically, you need to feed it some data with 0 values in appropriate places. With your data:

mydat <- cbind(rbind(a,b,0),rbind(0,0,c))[,c(1,6,2,7,3,8,4,9,5,10)]
barplot(mydat,space=c(.75,.25))

barplot

To see what's going on under the hood, take a look at mydat:

> mydat
  [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
a    3    0    3    0    2    0    1    0    0     0
b    3    0    2    0    2    0    2    0    2     0
     0    0    0    1    0    2    0    3    0     4

Here, you're plotting each bar with three values (the value of a, the value of b, the value of c). Each column of the mydat matrix is a bar, sorted so that the ab bars are appropriately interspersed with the c bars. You may want to play around with spacing and color.

Apparently versions of this have been discussed on R-help various times without great solutions, so hopefully this is helpful.

edited Mar 26 '14 at 20:24

answered Aug 06 '13 at 13:47

Thomas

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Yea, this is exactly what I wanted. Thanks. Any chance you could show me the equivalent ggplot? – Forzaa Aug 06 '13 at 13:54
@Forzaa I actually don't use ggplot, so I can't be any help there. – Thomas Aug 06 '13 at 13:57
No worries; I'll look into that myself. Thanks again, though! – Forzaa Aug 06 '13 at 14:00

score 0 · Answer 2 · edited Oct 23 '16 at 21:01

0

Try the lattice lib:

library("lattice")
MyData <- as.data.frame(Titanic)

barchart(Freq ~ Survived | Age * Sex, groups = Class, data = MyData,
         auto.key = list(points = FALSE, rectangles = TRUE, space
         = "right", title = "Class", border = TRUE), xlab = "Survived",
         ylim = c(0, 800))

As you can see the grouping and ploting is done at once.

Please also see: https://stat.ethz.ch/pipermail/r-help/2004-June/053216.html

edited Oct 23 '16 at 21:01

doncherry

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answered Aug 06 '13 at 13:14

maximus

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There is no stacking on top of each other in this example, so it does not really achieve my goal. – Forzaa Aug 06 '13 at 13:18

R: bar plot with two groups, of which one is stacked

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