# this was created in an attempt to make trellis plots in R
# like those found in the lattice package, but made from scratch
# to have more control for things like the ability to plot by column
# rather than by row. Share and modify as you like.
# Ian Taylor, June 20, 2006

nplots = 17 # can be adjusted a lot, but looks pretty silly above 100

# nrows and ncols chosen to make approximately square plot
# favoring slightly more rows than cols
nrows = ceiling(sqrt(nplots))
ncols = ceiling(nplots/nrows)
windim = c(7,7) #if windows(a,b) is called, replace this with c(a,b)
mardim = 0.7    #amount needed for axes
titledim = 0.5  #amount needed for title

# making a matrix to represent the positions and orders of the cells
layoutmat = matrix(1:(nrows*ncols),nrows,ncols, byrow=F) # change to byrow=T if desired
layoutmat[layoutmat>nplots] = 0 # zero out any cells beyond nplots
layoutmat = cbind(nplots+1:nrows,layoutmat) # add entries for vertical axis
layoutmat = rbind(layoutmat, c(0,nplots+nrows+1:ncols)) # add entries for horiz. axis
layoutmat = rbind(c(0,rep(nplots+nrows+ncols+1,ncols)),layoutmat) # centered over plots, not true center
# here's what layoutmat looks like at nplots=17
# zeros represent unused cells, repeated value
# across the top has those cells merged as a single cell

#     [,1] [,2] [,3] [,4] [,5]
#[1,]   27   27   27   27   27
#[2,]   18    1    6   11   16
#[3,]   19    2    7   12   17
#[4,]   20    3    8   13    0
#[5,]   21    4    9   14    0
#[6,]   22    5   10   15    0
#[7,]    0   23   24   25   26

nf = layout(layoutmat,respect=T,
    widths=c(mardim, rep((windim[1]-mardim)/ncols,ncols)),
    heights=c(titledim,rep((windim[2]-mardim-titledim)/nrows,nrows),mardim))
layout.show(nf) #this shows the layout in the R window

ymax=1.4
nbars = 10
for(i in 1:nplots) # plot the main cells
{
    par(mar=rep(0,4))
    xvals = barplot(runif(nbars), col='grey', axes=F, xlab='', ylab='', main='', ylim=c(0,ymax))
    legend('top', paste('plot ',i), bty='n')
    box()
    xlim1 = par()$usr[1:2] #saves the range of x created by barplot
}
for(i in 1:nrows) # plot the vertical axes
{
    par(mar=c(0,5.1,0,0)) # 5.1 chosen by trial and error, may require modification
    plot(0, type='n', xaxs='i', yaxs='i', ylim=c(0,ymax), axes=F, xlab='', ylab='ylab', main='')
    axis(2, at = seq(0,1,0.5))
    #mtext(side=2,line=3,'proportion')
}
for(i in 1:ncols) # plot the horizontal axes
{
    par(mar=c(5.1,0,0,0)) # 5.1 chosen by trial and error, may require modification
    plot(0, type='n', xaxs='i', yaxs='i', xlim=xlim1, axes=F, xlab='xlab', ylab='',main='')
    axis(1, at=xvals, labels=1:nbars)
    #mtext(side=1,line=3,'length bin (cm)')
}
par(mar=c(0,0,0,0)) # add a title
plot(0,0,type='n',xlab='',ylab='',main='',axes=F)
text(0,0,'big title',font=2, cex=2)