[R] Tick marks in lines.survfit

[Prof Brian Ripley]

What did the maintainer say?  (This is in a contributed package survival, 
see the posting guide.)

The help page says

     fit <- survfit(Surv(time, status) ~ sex, pbc,subset=1:312)
      plot(fit, mark.time=FALSE, xscale=365.24,
              xlab='Years', ylab='Survival')
      lines(fit[1], lwd=2, xscale=365.24)    #darken the first curve and add marks

and no marks appear.

It looks to me as if the problem is that the code has e.g.

                 deaths <- c(-1, ssurv$n.event[who])

and ssurv is a vector.  I think that should be x$n.event (in two places).


On Fri, 19 May 2006, Rachel Pearce wrote:

> I posted several months about the problem with adding tick marks to curves
> using lines.survfit.
>
> This occurs when lines.survfit is used to add a curve to survival curves
> plotted with plot.survfit. The help for this function implies that
> mark.time=TRUE thus:
>
> plot(pfsfit,conf.int=FALSE,xscale=365.25,yscale=100,xlab="Years",ylab="%
> surviving",lty=2,mark=3)
> lines(osfit,mark=3,col=1,lty=1,xscale=365.24,mark.time=TRUE)
>
> will add tick marks to the added curve in the same way that they appear on
> the first curve, but no permutation of mark, col, lty, etc. seems to produce
> tick marks. Has anyone found a solution to this problem?
>
> Rachel
>
> British Society of Blood and Marrow Transplantation
>
> 	[[alternative HTML version deleted]]
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595