Bar Graphs - R Graphics - page 47

Solution
First, scale the data to 100% within each stack. This can be done by using ddply() from the
plyr package, with transform() . Then plot the resulting data, as shown in Figure 3-20 :
library(gcookbook) # For the data set
library(plyr)
# Do a group-wise transform(), splitting on "Date"
ce <- ddply(cabbage_exp, "Date" , transform,
percent_weight = Weight / sum(Weight) * 100 )
ggplot(ce, aes(x = Date, y = percent_weight, fill = Cultivar)) +
geom_bar(stat = "identity" )
Figure 3-20. Proportional stacked bar graph