I want the graphic AVANT to be in first place
dt = data.frame(AVG=c("POT","TPOT"),AVANT=c(5000,4400),APRES=c(5020,6500))
data = gather(dt, key="measure",value="value",c("AVANT","APRES"))
ggplot(data,aes(x=AVG, y=value,fill=AVG))+geom_bar(stat='identity')+facet_wrap(~measure)