[R] Plotting K-M Curve when have several strata

p.b.pynsent p.b.pynsent at bham.ac.uk
Fri Mar 28 17:17:55 CET 2003

```Kevin,
If you really want to get control of the colours then pick up the
relevant returned values and pass them individually to lines().
foo[[2]] will hold time axis, foo[[8]] and [[9]]the upper and lower ci.
I actually feed the ci values into polygon() and am then able to
eg
fit.r <- survfit(Surv(fuperiod, censor), data=s.data, type=
"kaplan-meier", conf.type="plain", conf.lower="peto")
x <- c(0,fit.r[[2]]) #add at time 0
y <- c(1,fit.r[[5]])
plot(x,y, col="blue",type="n",xlab="Time (years)",ylab="Proportion
surviving")
xp <- c(x,rev(x))
yp <- c(1,fit.r[[8]],rev(fit.r[[9]]),1)
polygon(xp,yp,density=NULL,col="pink", border= "pink", lwd=0.5)
lines(x,y, col="blue",type="l",lwd=3)

Paul

On Wednesday, March 26, 2003, at 12:13  pm, Ko-Kang Kevin Wang wrote:

> Hi,
>
> If I have:
>   foo <- survfit(y ~ x)
> where y is a survival object and x is a n-level factor.  The
> documentation
> says when I plot(foo), the confidence intervals will not be plotted
> (which
> I guess is understandable as otherwise the plot will get really messy).
>
> I tried to plot with confidence intervals by using:
>   plot(foo, conf.int = TRUE)
> and indeed the resulting plot is messy.  However I'm just wondering if
> I
> can (suppose x is a 2-level factor) use different colours and line
> types
> for the confidence lines?  If I do:
>   plot(foo, conf.int = TRUE, col = 1:2)
> then I'll get two different colours.  What I would like is to then plot
> the confidence lines using lty = 2 (while keeping the colour).
>
> Can I do this?
>
> --
> Cheers,
>
> Kevin
>
> -----------------------------------------------------------------------
> -------
> /* Time is the greatest teacher, unfortunately it kills its students */
>
> --
> Ko-Kang Kevin Wang
> Master of Science (MSc) Student
> SLC Tutor and Lab Demonstrator
> Department of Statistics
> University of Auckland
> New Zealand
> Homepage: http://www.stat.auckland.ac.nz/~kwan022
> Ph: 373-7599
>     x88475 (City)
>     x88480 (Tamaki)
>
> ______________________________________________
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>
>
Prof. P. B. Pynsent,
Research and Teaching Centre,
Royal Orthopaedic Hospital,
Birmingham, B31 2AP, U.K.

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