library(survival)
cancer.dat <- read.table("cancer.dat", col.names=c("Age","Smear","Infil","Index","Blasts","Temp","Resp","Time","Status"))
time<-cancer.dat[,"Time"]
status<-1-cancer.dat[,"Status"]
attach(cancer.dat)
cancer.cox<-coxph(Surv(time,status)~Age+Smear+Infil+Index+Blasts)
summary(cancer.cox)

cancer.cox1<-coxph(Surv(time,status)~Age)
cancer.cox1
cancer.cox1.mart<-residuals(cancer.cox1,type="martingale")

plot(Age,cancer.cox1.mart,ylab="Martingale residual")
abline(h=0)
lines(lowess(Age,cancer.cox1.mart))

cancer.cox1.dev<-residuals(cancer.cox1,type="deviance")

plot(Age,cancer.cox1.dev,ylab="Deviance residual")
abline(h=0)
lines(lowess(Age,cancer.cox1.dev))
identify(Age,cancer.cox1.dev,n=1)

cancer.cox1.shoen<-residuals(cancer.cox1,type="schoenfeld")

plot(Age[status==1],cancer.cox1.shoen,xlab="Survival time",ylab="Schoenfeld residual")
abline(h=0)
lines(lowess(Age[status==1],cancer.cox1.shoen))

agroup<-cancer.dat[,"Age"]-45
agroup[agroup>=0]<-1
agroup[agroup<0]<-0
plot(survfit(Surv(time,status)~agroup),xlab="Survival Time in months",ylab="Proportion surviving",lty=1:2)
legend("topright",c("Under 45","45 and over"),lty=1:2)

survdiff(Surv(time,status)~agroup)