1.geom_abline和geom_hline ggplot(mtcars)+geom_point(aes(mpg,disp,colour=gear))+theme_bw()+geom_hline(yintercept=c(300,400),colour='red',linetype=2,size=2)+geom_vline(xintercept=c(20,25),colour='blue',linetype=3,size=3) image.png 2.geom_bar和geom_col 2.1 count or weight 数...