r - Annotation above bars:

Question

dodged bar plot in ggplot again has me stumped. I asked about annotating text above bars on here a few weeks back (LINK) and got a terrific response to use + stat_bin(geom="text", aes(label=..count.., vjust=-1)). I figured since I already have the counts I'll just supply them with out the .. before and after and I told stat_bin that the position was dodge. It lines them up over the center of the group and adjusts up and down. Probably something minor. Please help me to get the text over the bars.

mtcars2 <- data.frame(type=factor(mtcars$cyl), 
    group=factor(mtcars$gear))
library(plyr); library(ggplot)
dat <- rbind(ddply(mtcars2,.(type,group), summarise,
    count = length(group)),c(8,4,NA))

p2 <- ggplot(dat,aes(x = type,y = count,fill = group)) + 
    geom_bar(colour = "black",position = "dodge",stat = "identity") +
    stat_bin(geom="text", aes(position='dodge', label=count, vjust=-.6)) 

Answer 1

I was having trouble getting the position dodges to line up, so I ended up creating a position_dodge object (is that the right terminology?), saving it to a variable, and then using that as the position for both geoms. Somewhat infuriatingly, they still seem to be a little off centre.

dodgewidth <- position_dodge(width=0.9)
ggplot(dat,aes(x = type,y = count, fill = group)) + 
  geom_bar(colour = "black", position = dodgewidth ,stat = "identity") +
  stat_bin(geom="text", position= dodgewidth, aes(x=type, label=count), vjust=-1)