根据两条曲线形成多边形

Question

I have fit 3 separate logarithmic curves to a series of human growth data via maximum likelihood estimation. Each of these curves is plotted as follows:

cedar.plot.MEAN<-curve(cedar.estim.MEAN, from = 0, to = 18)
cedar.plot.MAX<-curve(cedar.estim.MAX, from = 0, to = 18, add = TRUE)
cedar.plot.MIN<-curve(cedar.estim.MIN, from = 0, to = 18, add = TRUE)

Femur length ~ MINAGE, MEANAGE, MAXAGE

Essentially, I would like to plot the middle curve - the Mean - bounded by a polygon of the upper and lower curve. I have tried the polygon function:

polygon(c(cedar.plot.MIN),c(cedar.plot.MAX),col = "grey75", border = FALSE)

But, the syntax is wrong. What is the best way to plot a polygon around the mean curve bounded by the upper and lower.

Answer 1

polygon needs the x and y coordinates of the points. Since you do not provide your functions, I cannot test, but you need something like

polygon(c(cedar.plot.MIN$x, rev(cedar.plot.MAX$x)), c(cedar.plot.MIN$y, rev(cedar.plot.MAX$y)), col="#88888833")

Here is a tested example.

C = curve(sin, from=0, to=12, ylim=c(-1,3))
C2 = curve(Sp2, from=0, to=12, add=TRUE)
polygon(c(C$x, rev(C2$x)), c(C$y, rev(C2$y)), col="#88888833")