[R] Strang line while plotting failure curves

Frank E Harrell Jr f.harrell at vanderbilt.edu
Thu Nov 6 19:21:43 CET 2008

Lu, Jiang wrote:
> Dear R helper,
> I encountered a problem when I tried to plot the cumulative failure rate
> (i.e. 1 - survival probability). I have used the following code to plot. The
> scenario is that patients are randomized to different treatment arm (rev in
> the code), the PCI revascularization was monitored over 5 years.
> #R code
>  testfit <- survfit(Surv(pcifu,pci)~rev,data=subproc)
>  testfit$surv <- 1 - testfit$surv
>  testfail <- plot(testfit, mark.time=FALSE,col=1:2, main='Failure Rate')
> #End of R code
> I arbitarily replaced testfit$surv by computing 1 minus the original
> survival rate. So far so good. However, when I plot the manipulated
> "testfit", there is a vertical line plotted at x=0, y=0:1. I checked
> testfit$time and testfit$surv, nothing weird there. I am very confused where
> the vertical line at starting point of time 0 came from. How can I get rid
> of it?
> Would you pleae help me with this? Thanks a lot!
> Jiang

Also see the survplot.* functions in the Design package and their fun 
argument, e.g., fun=function(y)1-y


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Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University

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