http://www.sthda.com/english/wiki/ggplot2-error-bars-quick-start-guide-r-software-and-data-visualization

效果图：

# 操作实例-----------------------

dat1 <- read.csv("~/Tudat.csv")

View(dat1)

attach(dat1)

library(ggplot2)  # install.packages("ggplot2")

p<-ggplot(data=dat1,aes(x=Gene,y=Ct,fill=grp))

p

# Keep only upper error bars

p+geom_bar(stat="identity", color="black", width = 0.6,position=position_dodge()) +

 geom_errorbar(aes(ymin=Ct,ymax=Ct+SD), width=0.2, position=position_dodge(0.6)) ->q

q

# geom_errorbar(width=)表示误差棒的相对宽度

# geom_errorbar(position=position_dodge(0.6))中的0.6 需与

# geom_bar(width=)的取值一样，否则误差棒会错位

## Finished bar plot

# 更改barplot到x轴的距离为0

q+scale_y_continuous(expand = c(0, 0), limits = c(0,150),breaks = seq(0, 150,by=30))  

# 改变legend的位置，box,title etc, 数值为相对值，从0到1

last_plot()+ theme(legend.position=c(0.1,0.9),legend.title = element_blank(),legend.background = element_rect(fill=NULL,size = 0.5,linetype = "solid",colour = "black"),panel.background = element_rect(fill = "white",colour="black"),panel.grid.major = element_blank(),panel.grid.minor = element_blank())

# 添加 xy轴labels和标题,添加文本,更改 标题位置为居中

last_plot()+ggtitle("Try mutil-y errorbar")+labs( x = "Gene(ser)",y='Ct(***)')+geom_text(aes(x="G7",y=140,label="(a)"))+theme(plot.title = element_text(hjust = 0.5))

# save tiff 300dpi

# 可能图片会乱码。最好直接保存Metafile to ppt

      # 图形ok了

#以下附属内容，仅供参考

ggsave(filename = "Ct-Gene.test.tiff", width = 4,height = 4,dpi = 300)

#### If need， 将需要断y轴的High数据组，以分面facet_grid的形式代替。

last_plot()+facet_grid(~Mark,scale="free",space = "free")

# If need, 绘制x y轴线

last_plot()+theme(axis.line = element_line(color="black", size = 0.5))