il me semble oui voila mon code for(i in 2:5){ x<-ggplot(data = test, aes(x=test[,a[1]],y=test[,a[i]]/test[,a[6]])) + geom_point() x<-x + xlab("Age (year cal.BP)")+ylab("Rate of reads") + labs(title=a[i]) x<-x + geom_line(color="black",size=0.2) assign(a[i],x) }