Comment by alaiacano

> s1 <- data.frame(x=c(1,2,3), y=c(7,8,7),series=rep("s1", 3))

> s2 <- data.frame(x=c(1,2,3,4), y=c(6,7,6,7), series=rep("s2", 4))

> s <- rbind(s1, s2)

> qplot(x, y, data=s, geom=c('point', 'line'), color=series)