library(survival)

 ghn <- read.table("gehan.dat", header=T)
 #ghn <- read.table("/home/jane/public_html/gehan.dat", header=T)
     # *.dead gives the censoring information. '1' is observed, '0' censored
attach(ghn) 
time <- c(X6.MP.time,control.time) 
group <- c(rep(1,21),rep(0,21))
dead <- c(X6.MP.dead, control.dead)

ghn.surv <- survfit(Surv(time, dead) ~ group, conf.type="log-log")  
 
 plot(ghn.surv, xlab="Weeks", ylab="Estimated survival function", 
       conf=T, lty=c(1,2))
    # include confidence intervals, use different line types 'lty' for groups
title(main="Remission of leukaemia patients")
legend(25,0.95, c("Controll","6MP"),lty=c(1,2))
   
t <- seq(0.1,max(time),0.1) # set up time for lines. 
 lines(t, exp(-21*t/182)) 
 
 lines(t, exp(-9*t/359), lty=2) 
 
ctl.exp <- survreg(Surv(control.time,control.dead) ~1, dist="exp")
mp.exp  <- survreg(Surv(time[group==1], dead[group==1]) ~ 1, dist="exp")

ghn.exp <- survreg(Surv(time, dead) ~ group, dist="exp")
  names(ghn.exp)
ghn.exp$coef  ; 
rho0 <- ghn.exp$coef[1] ; (rho1 <- rho0 + ghn.exp$coef[2])
lam0 <- exp(-rho0); lam1 <- exp(-rho1) 
 lines(t, exp(-lam0*t) ) ;  lines(t, exp(-lam1*t), lty=2 )

ctl.wei <- survreg(Surv(control.time,control.dead) ~1, dist="weib")
 mp.wei  <- survreg(Surv(time[group==1], dead[group==1]) ~ 1, dist="weib")
  ghn.wei <- survreg(Surv(time, dead) ~ group, dist="wei")
summary(ghn.wei)  ; names(ghn.wei) 
ghn.wei$coef ; alpha <- ghn.wei$scale
rho0 <- ghn.wei$coef[1] ; (rho1 <- rho0 + ghn.wei$coef[2])

Wlam0 <- exp(-ghn.wei$coef[1]); 

Wlam1 <- exp(-(ghn.wei$coef[1]+ghn.wei$coef[2])) 

 lines(t, exp( -(lam0*t)^alpha ) );  lines(t, exp( -(lam1*t)^alpha ) , lty=2 )
   lines(t, exp( -(lam0*t)^alpha ) ,lty=3)
   lines(t, exp( -(lam1*t)^alpha ) , lty=4 )


ctl.ll <- survreg(Surv(control.time,control.dead) ~1, dist="logl")
 mp.ll  <- survreg(Surv(time[group==1], dead[group==1]) ~ 1, dist="logl")
ghn.ll <- survreg(Surv(time, dead) ~ group, dist="logl")