Question

I have all the parameters fixed to describe one plot including oma, mar, mgp, … I want to divide the very plot area into several separate, exactly equally sized smaller plot areas which share both x and y label. For example something like this:

I found solutions to combine plots but with seperate axes. Any starting point for the problem here?

Answer 1

You can set the outer margins to be big enough to hold the axes and labels, then set the regular margins to 0. Use par(mfrow or layout to split the inner region into the panels that you want, then do the plots without the axes and labels and add the axes and labels into the outer margins:

par( oma=c(5,4,4,1)+0.1, mar=c(0,0,0,0) )
layout( matrix( 1:3, nrow=1 ) )
for( i in levels(iris$Species) ) {
    with( iris[ iris$Species==i, ], {
        plot(Sepal.Width, Sepal.Length, ann=FALSE, xaxt='n', yaxt='n',
            ylim=range(iris$Sepal.Length))
        axis(1, outer=TRUE)
        mtext(side=3, i ) }
    )
}
axis(2, outer=TRUE)

But it is probably simpler using lattice or ggplot2.