From: Frank E Harrell Jr <f.harrell_at_vanderbilt.edu>

Date: Wed 31 May 2006 - 06:04:47 EST

Date: Wed 31 May 2006 - 06:04:47 EST

Osman Al-Radi wrote:

> Dear R-help

*>
**> How can one get survplot() to place the number at risk just below the
**> survival curve as opposed to the default which is just above the x-axis?
**> I tried the code bellow but the result is not satisfactory as some numbers
**> are repeated several times at different y coordinates and the position of
**> the n.risk numbers corresponds to the x-axis tick marks not the survival
**> curve time of censoring.
**>
**> n <- 20
**> set.seed(731)
**> cens <- 15*runif(n)
**> h <- .02*exp(2)
**> dt <- -log(runif(n))/h
**> label(dt) <- 'Follow-up Time'
**> e <- ifelse(dt <= cens,1,0)
**> dt <- pmin(dt, cens)
**> units(dt) <- "Year"
**> S <- Surv(dt,e)
**> km<-survfit(S~1)
**> survplot(km,n.risk=T,conf='none', y.n.risk=unique(summary(km)$surv))
**>
**> Any suggestion on addressing this problem would be apprecited.
**>
**> Also, is there a way to add a tick mark to the survival curve at times of
**> censoring similar to the mark.time=T argument in plot.survplot()?
**>
**> Thanks
**>
**> Osman
**>
*

Osman,

y.n.risk has to be a scalar and gives the y-coordinate of the bottom line of number at risk. I take it that you want the numbers not all at the same height. This will require a customization of survplot or fetching information from the km object and using text( ).

Frank

-- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.htmlReceived on Wed May 31 07:12:23 2006

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