[R] How to access results of survival analysis

Xiaochun Li xiaochun at jimmy.harvard.edu
Fri May 5 16:40:33 CEST 2006

Hi List,

A friend of mine recently asked the same question as Heinz Tüchler.  Since
I've already written the code I'd like to share with the list.

# x is an object returned by "survfit";
# "smed" returns a matrix of 5 columns of
# n, events, median, 0.95LCL, 0.95UCL.
# The matrix returned has rownames as the
# group labels (eg., treatment arms) if any.

smed <- function(x) {
        ox <- capture.output(print(x))
        n <- length(ox)
        tmp <- t(sapply(ox[4:n],          
                function(l) strsplit(l, split=' +')[[1]]))
        nres <- strsplit(ox[3],split=' +')[[1]][2:6]
        res <- matrix(as.numeric(tmp[,2:6]), ncol=5,
                dimnames=list(tmp[,1], nres))

# example:


fit1 <- survfit(Surv(time, status) ~ 1, data=aml)   
sf1 <- smed(fit1)

fit <- survfit(Surv(time, status) ~ x, data=aml)
sf <- smed(fit)

Xiaochun Li, Ph.D.
Research Scientist
Department of Biostatistics and Computational Biology
Dana Farber Cancer Institute
Harvard School of Public Health

(617) 632 3602

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