[R] Function comparable to cutpt.coxph from "Survival Analysis using S"

[Terry Therneau]

  Quoting Frank H: "These relationships rarely occur in nature..."  I
agree; I have seen cutpoint relationships only a handful of times in 25
years of medical work.
  A better approach is to look at the data using a smoothing spline:
     options(na.action=na.exclude)
     fit <- coxph(Surv(time,status) ~ age + weight + pspline(x))
     temp <- predict(fit, type='terms')
     plot(x, temp[,3])
My primary goal has always been to learn rather than to test.
It is common to see upper or lower thresholds, but not cutpoints.

Terry T.