Bar Graphs - R Graphics - page 33

Using Colors in a Bar Graph

Problem
You want to use different colors for the bars in your graph.

Solution
Map the appropriate variable to the fill aesthetic.
We'll use the uspopchange data set for this example. It contains the percentage change in pop-
ulation for the US states from 2000 to 2010. We'll take the top 10 fastest-growing states and
graph their percentage change. We'll also color the bars by region (Northeast, South, North Cen-
tral, or West).

First, we'll take the top 10 states:

library(gcookbook) # For the data set
upc <- subset(uspopchange, rank(Change) > 40 )
upc

State Abb Region Change
Arizona AZ West 24.6

Colorado CO West 16.9

Florida FL South 17.6

Georgia GA South 18.3

Idaho ID West 21.1

Nevada NV West 35.1

North Carolina NC South 18.5

South Carolina SC South 15.3

Texas TX South 20.6

Utah UT West 23.8

Now we can make the graph, mapping Region to fill ( Figure 3-9 ):

ggplot(upc, aes(x = Abb, y = Change, fill = Region)) + geom_bar(stat = "identity" )