Cloud2016 已更改， 但是我好像没有@你来回答我的提问

library(ggplot2)

# Base Plot
g <- ggplot(mpg, aes(x=displ, y=hwy)) + 
  geom_point() +
  facet_grid(manufacturer ~ class)  

plot(g1)

[代码来源](http://r-statistics.co/Complete-Ggplot2-Tutorial-Part2-Customizing-Theme-With-R-Code.html）

问题 :
1. 使用facet_grid之后 每个图片过小看不清坐标。所以想把7列变为一列，每行只放一张图 。排完colname(mpg)[1], 再排colname(mpg)[2] .... 按序排列。
2. 调整图片大小

Data

ID <- 1:20
conc <- round(rnorm(20, 100, 20), 1)
gene <- c("GA", "AT", "AT", "GA", "GA", "AT", "TT", "TT", "GA", "GG", "GA", "AT", "GT", "TT", "GT", "GA", "GT", "AT", "GT", "GG")
dt <- data.frame(ID, conc, gene)
dt[,3] = lapply(dt[,3],function(x) factor(x, levels=c("GA", "AT", "TT", "GG", "GT"))) # 运行到这里会出错

加上这一步骤的原因是， 尽管某个level缺失也要在x轴上标记出来，以防程序自动省略掉， 就是让数据循环中的每一个图保持这五个level。

错误提示

Warning message:
In [<-.data.frame(*tmp*, , 3, value = list(1L, 2L, 2L, 1L, 1L, :
provided 20 variables to replace 1 variables

绘图

boxplot(conc~as.factor(gene), data=dt, xaxt="n")
beeswarm(conc~as.factor(gene), data=dt, col="deeppink")

axis

axis(1, at=1:5, labels=c(paste0("GA","\n n=",length(dt[,2]=="GA")),
paste0("AT","\n n=",length(dt[,2]=="AT")),
paste0("TT","\n n=",length(dt[,2]=="TT")),
paste0("GG","\n n=",length(dt[,2]=="GG")),
paste0("GT","\n n=",length(dt[,2]=="GT"))))

请指教！