我有一个类似于这个的情节:
b <- data.frame(x=c(1,2,3,1,2,3,1,2,3,1,2,3),y=c(1,2,3,1.5,1.9,2.5,3,2,1,2.9,1.8,1.5),c=c("1","1","1","2","2","2","1","1","1","2","2","2"),f=c("b","b","b","b","b","b","a","a","a","a","a","a"))
ggplot(b,aes(x=x,y=y,color=c,group=c))+geom_line()+facet_grid(f ~ .)
现在我只希望上面刻面“a”中的线“1”更粗更虚线。这可能吗?