adjust plot parameters in R while plotting regsubsets object in R (more room below x axis)

Question

I'm trying to adjust the plotting parameters that I would normally do with par(mar=c(10,4.1,4.1,2.1) to allow for more room below the x-axis to plot these labels. Right now the variable names are running off the screen.

Is it something with the leaps package or the regsubsets object that I'm plotting that doesn't recognize the par(mar=c(10,4.1,4.1,2.1))

Here's a boiled down example of what I'm trying to do.

require('leaps')
par(mar=c(10,4.1,4.1,2.1))
leaps <- regsubsets(mpg~disp+hp+drat+wt+qsec, data=mtcars, nbest=2, nvmax=5)
## artificially making labels longer... my labels are longer than this example dataset
labs <- sapply(leaps$xnames, function(x) paste(rep(x,5), collapse='')) 
plot(leaps, scale=c('adjr2'), labels=labs))

Answer 1

This is caused by the function (plot.regsubsets()) setting mar within the function body. This overrides the mar that you set.

You can fix this by adding a mar argument to the plot.regsubsets() function and passing it to the par() call on line 3 of the function body:

plot.regsubsets<-function(x,labels=obj$xnames,main=NULL,
                          scale=c("bic","Cp","adjr2","r2"),
                          col=gray(seq(0,0.9,length=10)),mar = c(7,5,6,3)+0.1, ...){
    obj<-x
    lsum<-summary(obj)
    par(mar=mar)
    nmodels<-length(lsum$rsq)
    np<-obj$np
    propscale<-FALSE
    sscale<-pmatch(scale[1],c("bic","Cp","adjr2","r2"),nomatch=0)
    if (sscale==0)
        stop(paste("Unrecognised scale=",scale))
    if (propscale)
        stop(paste("Proportional scaling only for probabilities"))

    yscale<-switch(sscale,lsum$bic,lsum$cp,lsum$adjr2,lsum$rsq)
    up<-switch(sscale,-1,-1,1,1)

    index<-order(yscale*up)

    colorscale<- switch(sscale,
                        yscale,yscale,
                        -log(pmax(yscale,0.0001)),-log(pmax(yscale,0.0001)))

    image(z=t(ifelse(lsum$which[index,],
          colorscale[index],NA+max(colorscale)*1.5)),
          xaxt="n",yaxt="n",x=(1:np),y=1:nmodels,xlab="",ylab=scale[1],col=col)

    laspar<-par("las")
    on.exit(par(las=laspar))
    par(las=2)
    axis(1,at=1:np,labels=labels)
    axis(2,at=1:nmodels,labels=signif(yscale[index],2))

    if (!is.null(main))
        title(main=main)
    box()
    invisible(NULL)
}