如何重新缩放一个点矩阵?

Now I'm doing it this way:

现在我这样做:

d = approx(density(csvdata[,'X'],n=5000),xout=csvdata[,'X'])
dfact = 40/max(d$y)
for(i in 1:nrow(csvdata)) {
  d$y[i] = (d$y[i]*dfact)-20
}
d = appr