r - 查找密度图中前 10% 的截断点

Question

我想对本地化前 10% 的区域进行着色。我只是随意放置截断点 65，以绘制此图。这就是我打算找到的......对于每个数据集。

xf <- rnorm(40000, 50, 10);
plot(density(xf),xlim=c(0,100), main = paste(names(xf), "distribution"))
dens <- density(xf)
x1 <- min(which(dens$x >= 65)) # I want identify this point such that 
# the shaded region includes top 10%

x2 <- max(which(dens$x <  max(dens$x)))
with(dens, polygon(x=c(x[c(x1,x1:x2,x2)]), y= c(0, y[x1:x2], 0), col="green"))
abline(v= mean(traitF2),  col = "black", lty = 1, lwd =2)

Answer 1

我认为您正在寻找 quantile()功能:

xf <- rnorm(40000, 50, 10)
plot(density(xf),xlim=c(0,100), main = paste(names(xf), "distribution"))
dens <- density(xf)
x1 <- min(which(dens$x >= quantile(xf, .90))) # quantile() ftw!

x2 <- max(which(dens$x <  max(dens$x)))
with(dens, polygon(x=c(x[c(x1,x1:x2,x2)]), y= c(0, y[x1:x2], 0), col="green"))