graphics.off() trellis.device(color=F) xyplot(IA~delta|which, data=IAFA.df, strip= function(...) strip.default(..., style = 1), panel=function(x,y,subscripts=T){ ind<-max(subscripts)/201 panel.xyplot(x,y,type="l") z<-IAFA.df[subscripts,2] panel.xyplot(x,z,type="l",lwd=3) }, layout = c(3,1), xlab="delta", ylab="power", aspect="xy")