Rachel Pearce wrote:

I am sorry that this is another novice question. I am having trouble
using "legend" with the survival curve plot from the survival package,
and I wonder if it is because I have rescaled my plot.


Here is the relevant segment of code:


plot(survfit(Surv(OS,Status)~shortishcr1),main='Overall Survival by

factor', + xlab='Years',ylab='% surviving',lty=c(1,2),xscale=365.25,yscale=100)

legend(5,80,c('Factor=1','Factor=2'),lty=c(1,2))


Here the variable OS is in days, but I want to plot it in years, so I
scale it; likewise y is scaled to a percentage.
I am trying to position the legend in the rescaled x and y values.
Legend returns no error, but no legend appears on the plot.


Ask for the real coordinatre system using
  par("usr")
and place the legend somewhere appropriate within these user coordinates.

Uwe Ligges


If I exclude the scaling altogether:


plot(survfit(Surv(OS,Status)~shortishcr1),main='Overall Survival by

factor', + xlab='Years',ylab='% surviving',lty=c(1,2),)

legend(1825,.8,c('Factor=1','Factor=2'),lty=c(1,2))


then the legend appears exactly as expected.

Using the unscaled version of the legend call with the scaled plot,
however, again no legend appears but no error is returned.

I suspect I am making some elementary mistake, but I just can't see it.
It is so elementary that I can't find a similar question in the
archives. Can someone help?

Here is my version information:
_ platform i386-pc-mingw32
arch i386 os mingw32 system i386, mingw32 status major 2 minor 0.1 year 2004 month 11 day 15 language R



Rachel

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