Utilise Surv object in ggplot or lattice
- by Misha
Anyone know how to take advantage of ggplot or lattice in doing survival analysis? It would be nice to do trellis/facet like survival graphs.
So in the end I played around and sort of found a solution for a kaplan meier plot. Apologize for the messy code in taking the list elements into a dataframe, but I couldnt figure out another way.
Note: It only works with two levels of stratum. If anyone know how I can use x<-length(stratum) to do this please let me know (in stata I could append to a macro-unsure how this works in R)...
ggkm<-function(time,event,stratum) {
m2s<-Surv(time,as.numeric(event))
fit <- survfit(m2s ~ stratum)
f$time<-fit$time
f$surv<-fit$surv
f$strata<-c(rep(names(fit$strata[1]),fit$strata[1]),rep(names(fit$strata[2]),fit$strata[2]))
f$upper<-fit$upper
f$lower<-fit$lower
r<-ggplot (f,aes(x=time,y=surv,fill=strata,group=strata))+geom_line()+geom_ribbon(aes(ymin=lower,ymax=upper),alpha=0.3)
return(r)
}
