[R] 누적막대그래프 그리기(ggplot2)

S<-read_excel("C:/Users/p/Desktop/total.xlsx",sheet="SEC")                                            

Sd<-S[order(S$stage,decreasing=True,)]  
ggplot(S,aes(x=sample,y=Concentration,fill=stage))+geom_bar(stat="identity",position=position_stack(reverse=TRUE),colour='white')+facet_grid(.~Heavymetal)+scale_fill_manual(values=c(Fraction3="grey20",Fraction2="grey50",Fraction1="grey80"),name="",breaks=c("Fraction3","Fraction2","Fraction1"))+xlab("")+theme_bw()