可以查看segmented包求拐點的例子。

R中運行：

library(segmented)

？segmented

。。。。。。

#An example using the default method:

# Cox regression with a segmented relationship  
## Not run: 

library(survival)

data(stanford2)

o<-coxph(Surv(time, status)~age, data=stanford2)

os<-segmented(o, ~age, psi=40) #estimate the breakpoint in the age effect

summary(os) #actually it means summary.coxph(os)

plot(os) #it does not work

plot.segmented(os) #call explicitly plot.segmented() to plot the fitted piecewise lines

如圖，拐點已求出。