熊荣川

六盘水师范学院生物信息学实验室

[email protected]    

http://blog.sciencenet.cn/u/Bearjazz 

箱体图，或箱形图是科学研究、统计分析中常常用到的统计图形。毫无疑问R语言能绘制各种各样的箱体图。下面是来自R自身帮助包中的实例（http://127.0.0.1:13367/library/graphics/html/boxplot.html）。此处只是将相应的效果图片补充完整，增加参考性和便捷性。部分地方有我们自己的中文注释，但是不值一提。

## boxplot on a formula:

boxplot(count ~ spray, data = InsectSprays, col ="lightgray")

# *add* notches (somewhat funny here):

boxplot(count ~ spray, data = InsectSprays,

      notch = TRUE, add = TRUE, col = "blue")

#使用add选项把新的图叠加的上一个图上

#使用notch选项，画出“缺口”如果两个箱形图缺口部分不重叠，说明中值差异显著

boxplot(decrease ~ treatment, data =OrchardSprays,

      log = "y", col = "bisque")

#将y值设为log scale

rb <- boxplot(decrease ~ treatment, data= OrchardSprays, col = "bisque")

title("Comparing boxplot()s andnon-robust mean +/- SD")

#使用title函数加标题

#在上图上叠加均值和标准差

mn.t <- tapply(OrchardSpraysdecrease,OrchardSpraysdecrease,OrchardSpraystreatment, mean)

sd.t <- tapply(OrchardSpraysdecrease,OrchardSpraysdecrease,OrchardSpraystreatment, sd)

xi <- 0.3 + seq(rb$n)

points(xi, mn.t, col = "orange",pch = 18)

arrows(xi, mn.t - sd.t, xi, mn.t + sd.t,

     code = 3, col = "pink", angle = 75, length = .1)

#下面演示怎样用表格中的几列数据做箱形图（之前的数据都是在同一列的哦）

## boxplot on a matrix:

mat <- cbind(Uni05 = (1:100)/21, Norm =rnorm(100),

           `5T` = rt(100, df = 5), Gam2 = rgamma(100, shape = 2))

boxplot(as.data.frame(mat),

      main = "boxplot(as.data.frame(mat), main = ...)")

#旋转、水平作图，箱体图

par(las = 1) # all axis labels horizontal

boxplot(as.data.frame(mat), main ="boxplot(*, horizontal = TRUE)",

      horizontal = TRUE)

## Using 'at = ' and adding boxplots --example idea by Roger Bivand :

#使用at选项制定箱体图输出的位置

boxplot(len ~ dose, data = ToothGrowth,

      boxwex = 0.25, at = 1:3 - 0.2,

      subset = supp == "VC", col = "yellow",

      main = "Guinea Pigs' Tooth Growth",

      xlab = "Vitamin C dose mg",

      ylab = "tooth length",

      xlim = c(0.5, 3.5), ylim = c(0, 35), yaxs = "i")

#叠加到上图，at选项使得位置错开

#对部分类别数据作图

boxplot(len ~ dose, data = ToothGrowth, add= TRUE,

      boxwex = 0.25, at = 1:3 + 0.2,

      subset = supp == "OJ", col = "orange")

legend(2, 9, c("Ascorbic acid","Orange juice"),

     fill = c("yellow", "orange"))

#添加图例，

## more examples in  help(bxp)

转载自：http://blog.sciencenet.cn/blog-508298-746662.html