plot function in R producing legend without legend() being called

Question

I'm trying to produce a cumulative incidence plot for a competing hazards survival analysis using plot() in R. For some reason, the plot that is produced has a legend that I have not called. The legend is intersecting with the lines on my graph and I can't figure out how to get rid of it. Please help!

My code is as follows:

CompRisk2 <- cuminc(ftime=ADI$time_DeathTxCensor, fstatus=ADI$status, group=ADI$natADI_quart)
cols <- c("darkorange","coral1","firebrick1","firebrick4","lightskyblue","darkturquoise","dodgerblue","dodgerblue4")
par(bg="white")
plot(CompRisk2,
     col=cols,
     xlab="Years",
     ylab="Probability of Mortality or Transplant",
     xlim=c(0,10),
     ylim=c(0,0.6))

Which produces the following plot:

I tried adding the following code to move the legend out of the frame, but I got an error:

legend(0,5, legend=c(11,21,31,41,12,22,32,42),
col=c("darkorange","coral1","firebrick1","firebrick4","lightskyblue","darkturquoise","dodgerblue","dodgerblue4"),
lty=1:2, cex=0.8, text.font=4, box.lty=0)

Error: Error in title(...) : invalid graphics parameter

Any help would be much appreciated!

Answer 1

I don't think that the ellipsis arguments are intended for the legend call inside plot.cuminc. The code offered in Ben's answer suggests that there might be a wh argument that determines the location of the legend. It is not named within the parameters as "x" in the code he offered, but is rather given as a positionally-defined argument. If you look at the plot.cuminc function you do in fact find that wh is documented.

I cannot test this because you have not offered us access to the ADI-object but my suggestion would be to try:

opar <- par(xpd=TRUE) # xpd lets graphics be placed 'outside'
plot(CompRisk2,
     col=cols, wh=c(-.5, 7), 
     xlab="Years",
     ylab="Probability of Mortality or Transplant",
     xlim=c(0,10),
     ylim=c(0,0.6))
 par(opar)  # restores original graphics parameters

It's always a bit risky to put out a code chunk without testing, but I'm happy to report that I did find a suitable test and it seems to work reasonably as predicted. Using the code below on the object in the SO question prior question about using the gg-packages for cmprsk:

library(cmprsk)
# some simulated data to get started
comp.risk.data <- data.frame("tfs.days" = rweibull(n = 100, shape = 1, scale = 1)*100,
                             "status.tfs" = c(sample(c(0,1,1,1,1,2), size=50, replace=T)),
                             "Typing" = sample(c("A","B","C","D"), size=50, replace=T))

# fitting a competing risks model
CR <- cuminc(ftime = comp.risk.data$tfs.days, 
             fstatus = comp.risk.data$status.tfs, 
             cencode = 0,
             group = comp.risk.data$Typing)

opar <- par(xpd=TRUE) # xpd lets graphics be placed 'outside'
plot(CR,
      wh=c(-15, 1.1),  # obviously different than the OP's coordinates
     xlab="Years",
     ylab="Probability of Mortality or Transplant",
     xlim=c(0,400),
     ylim=c(0,1))
par(opar)   # restores graphics parameters

I get the legend to move up and leftward from its original position.