生物信息学生R入门教程–绘图基础

柱状图

普通的柱状图使用barplot函数。其参数horiz=TRUE表示水平画图，beside=TRUE表示如果是多组数据的话，并排画图，否则原位堆叠画图。

> op <- par(mfrow = c(1, 2))
> counts <- table(mtcars$vs, mtcars$gear)
> barplot(counts, main = "Car Distribution by Gears and VS", xlab = "Number of Gears", 
+     col = c("darkblue", "red"), legend = rownames(counts), horiz = TRUE)
> barplot(counts, main = "Car Distribution by Gears and VS", xlab = "Number of Gears", 
+     col = c("darkblue", "red"), legend = rownames(counts), beside = TRUE)

> par(op)

柱状统计图使用hist函数。其breaks参数设置每组的范围。可以使用loess回归后计算出一条拟合曲线。对于hist图像，还可以使用density函数拟合曲线。

> h <- hist(mtcars$mpg, breaks = 12)
> lo <- loess(h$counts ~ h$mids)
> x <- seq(min(h$breaks), max(h$breaks), (max(h$breaks) - min(h$breaks))/1000)
> lines(x, predict(lo, x), col = "red")
> dens <- density(mtcars$mpg)
> t <- dens$n * length(dens$x)/sum(h$counts)/length(h$counts)/sum(h$density)
> lines(dens$x, dens$y * t, col = "blue")