斜体部分标题

Question

a want to plot some graphs from for loop, where the main should be half italic and half normal. The code example should be

 a1<-1:20
 a2<-sample(a1)
 b1<-sample(a1)
 b2<-sample(a1)
 a<-list(a1, a2)
 b<-list(b1, b2)
 v<-c("a", "b")
 for(i in 1:2){
 jpeg(file=sprintf("%s.jpg", v[i]))
 plot(a[[i]], b[[i]], main=c("sas", v[i]))
 dev.off()}

but the v[i] should be in italic. I tried

 plot(a[[i]], b[[i]], main=c("sas", expression(italic(v[i]))))

but the second line of main is missing. Thx for any ideas!

Answer 1

How about

 plot(a[[i]], b[[i]], main=bquote("sas"~italic(.(v[i]))))

That produces

Of if you realy wanted two lines, you could do

plot(a[[i]], b[[i]], main=bquote(atop("sas",italic(.(v[i])))))