`plot.密度` 将“xlim”扩展到我的数据范围之外。为什么以及如何解决它？

使用下面的代码，我试图获取不同分布的密度图。

dens <- apply(df[,c(7,9,12,14,16,18)], 2, density)

plot(NA, xlim=range(sapply(dens, "[", "x")), ylim=range(sapply(dens, "[", "y")))
mapply(lines, dens, col=1:length(dens))

legend("topright", legend=names(dens), fill=1:length(dens),bty = "n",lwd=1, cex=0.7)

The maximum upper limit for all variables is 5. But I got lines exceeded the 5. What do I need to change in my code to fix the plot?

默认情况下，density将扩大范围，使密度曲线在极值处接近 0。您想将曲线限制在您的数据范围内吗？如果是这样，您需要使用from and to里面的争论density().

x_range <- range(df[,c(7,9,12,14,16,18)])
dens <- apply(df[,c(7,9,12,14,16,18)], 2, density, from = x_range[1], to = x_range[2])

也许最好提供一个可重现的例子。

set.seed(0); X <- matrix(rnorm(300), 100, 3)

## range of your data
x_range <- range(X)
# [1] -2.904899  2.658658

## default handling of `density`
dens <- apply(X, 2, density)
range(sapply(dens, "[[", "x"))
# [1] -3.922346  3.696451

## customized `from` and `to`
dens <- apply(X, 2, density, from = x_range[1], to = x_range[2])
range(sapply(dens, "[[", "x"))
# [1] -2.904899  2.658658