Add subgroup labels to a jitter plot in ggplot2

Question

I have a nearly-boxplot like jitter-plot:

dt <- rbind(se,cb,cb.se)
qplot(ds, size, data=dt, geom="jitter", colour=root, facets = test ~ .)

I'd love to put a summary label for each group in the middle of the plot - for example the size totals here:

 aggregate(list(size=dt$size), list(dt$ds, dt$test), sum)

   Group.1  Group.2   size
1     b217       se   9847
2      c10       se  97296
3     c613       se  21633
4       c7       se 207540
...

I've tried using + geom_text(aes(x=ds, y=128, label=sum(size)), size=2) to add labels, but I get the same label on each position - how can I get the sum of just that section of data?

Edit: Here's where I'm at now - maybe I'm just going in the wrong direction

data <- rbind(se,cb,cb.se)
labels <-ddply(data, c("ds", "test"), function(df) sum(df$size))
ggplot(data=data, aes(x=ds)) +
  geom_jitter(aes(y=size, colour=root)) +
  geom_text(data=labels, aes(x=ds, y=600, label=V1), size=3) +
  facet_wrap(test ~ .)

This code doesn't work - I get an undefined columns selected error... somewhere. Maybe it's because of the multiple data= sections?

Answer 1

Take a look here. It may be helpful Adding direct labels to ggplot2 and lattice plots