在 R 中为绘图的 3 个区域着色

Question

我有一个图，其中有两条曲线（如下）。

我想知道是否有办法在红色的顶线上方、黄色的两条线之间和下方着色green?

中的底线

我想要的情节以及我的可重现代码如下。

f <- function(x,peak_x=10,peak_y=11,coef=.004) coef*-(x-peak_x)^2+peak_y
a <- curve(f,0,65,ylim=c(0,11))
b <- curve(f(x, peak_y = 6,coef = .003),0,65, col=3,add=TRUE)

Answer 1

可能有几种方法，但是polygon很好：

## define function
f <- function(x, peak_x, peak_y, coef) coef * -(x - peak_x)^ 2 + peak_y

## base plot
plot(NA, type="l", xlim=c(0,65), ylim=c(0,11))

## coordinates of user plotting space
pusr <- par("usr")

## x points to cover the whole area
x <- seq(pusr[1], pusr[2], length.out=101)

## then plot the polygons associated with the curves
rect(pusr[1], pusr[3], pusr[2], pusr[4], col=2)
polygon(x = c(x, pusr[1]), y = c(f(x, 10, 11, 0.004), pusr[3]), col="yellow")
polygon(x = c(x, pusr[1]), y = c(f(x, 10,  6, 0.003), pusr[3]), col="green")

Answer 2

正确答案可通过以下方式获得：

a <- curve(f,-3,65,ylim=c(0,12),xaxs="i",yaxs="i")
pusr <- par("usr")
rect(pusr[1], pusr[3], pusr[2], pusr[4], col=2,border = 1)
b <- curve(f(x, peak_y = 6,coef = .003),-3,65,add=TRUE,col=2)


polygon(c(-3,a$x,63),c(0,a$y,f(63)),col="yellow")
polygon(c(-3,b$x,54),c(-3,b$y,f(55, peak_y = 6,coef = .003)),col=3)
box()

在 R 中为绘图的 3 个区域着色

Coloring 3 regions of a plot in R

plot

r

function

polygon