如何使用 Polygon() 在概率密度曲线下方着色

我无法获取polygon()遮荫below分布一直到 x 轴。它似乎在指数分布之上y=-x线。这是我到目前为止所拥有的：

x <- seq(0,50,0.01)
y <- dexp(seq(0,50,0.01),rate=0.11)
plot(x, y, type="l", col=col2rgb("yellow",0.5), xaxs="i", yaxs="i", ylim=c(0,0.15))
polygon(x, y ,border=NA,col=col2rgb("yellow",0.5))

非常感谢！

解决方案很简单，通过adding (0,0)到多边形的顶点。见下文：

x <- seq(0,50,0.01)
y <- dexp(seq(0,50,0.01),rate=0.11)
plot(x, y, type="l", col=col2rgb("yellow",0.5), xaxs="i", yaxs="i", ylim=c(0,0.15))
polygon(c(0, x), c(0, y), border=NA, col=col2rgb("yellow",0.5))

How polygon() works

polygon() will 按顺序排列所有顶点。您原始代码的问题在于来源(0, 0)不是顶点之一，因此它不会是多边形的一部分。您还可以考虑以下玩具示例：

x0 <- c(0, 0.5, 1.5)
y0 <- c(1.5, 0.5, 0)
## triangle, with three vertices
plot(x0, y0, pch = ".")
polygon(x0, y0, col = "red", border = NA)
## area under triangle, four vertices
polygon(c(0, x0), c(0, y0), col = "yellow", border = NA)