R geom_tile ggplot2 what kind of stat is applied?

Question

I used geom_tile() for plot 3 variables on the same graph... with

tile_ruined_coop<-ggplot(data=df.1[sel1,])+
  geom_tile(aes(x=bonus, y=mal         


        

Answer 1

It uses stat_identity as can be seen in the documentation. You can test that easily:

DF <- data.frame(x=c(rep(1:2, 2), 1), 
                 y=c(rep(1:2, each=2), 1), 
                 fill=1:5)

#  x y fill
#1 1 1    1
#2 2 1    2
#3 1 2    3
#4 2 2    4
#5 1 1    5

p <- ggplot(data=DF) +
  geom_tile(aes(x=x, y=y, fill=fill))

print(p)

As you see the fill value for the 1/1 combination is 5. If you use factors it's even more clear what happens:

p <- ggplot(data=DF) +
  geom_tile(aes(x=x, y=y, fill=factor(fill)))

print(p)

If you want to depict means, I'd suggest to calculate them outside of ggplot2:

library(plyr)
DF1 <- ddply(DF, .(x, y), summarize, fill=mean(fill))
p <- ggplot(data=DF1) +
  geom_tile(aes(x=x, y=y, fill=fill))

print(p)

That's easier than trying to find out if stat_summary can play with geom_tile somehow (I doubt it).