[R] ggplot2 - tricky problem

Hello, R friends,  I've been struggling quite a bit with ggplot2. Having worked through Hadleys book twice I still wonder how to solve this task. 1. Short example Dataframe: id    city    Likeability    Uniqueness 1    Berlin    5    3 2    Munich    4    4 3    Berlin    6    4 4    Munich   

Re: [R] ggplot2 - tricky problem

how bout: dat-data.frame(id=1:4,city=c('berlin','munich'),likeability=c(5,4,6,5),uniqueness=c(3,4,4,4)) ggplot(ddply(melt(dat, id.vars=c('id','city')), .(variable,city), summarise, value=mean(value)),