A low-level way to organize plots in a grid

stack_plots-v1.R

"""
A better way uses the gridExtra package. This is mostly for future reference, in case gridExtra doesn't
handle a specific case.
"""

# Stacking plots in a grid
stack_plots <- function(gs, nrow, ncol, fout=NULL, add_opts){
  # example: stack_plots(list(g1, g2, g3), 2, 2, function (x) opts(legend.position="bottom"))

  if(length(fout) > 0){
    pdf(fout, width=17, height=10)
  }

  grid.newpage()
  pushViewport(viewport(layout=grid.layout(nrow,ncol)))
  vplayout <- function(x, y) viewport(layout.pos.row = x, layout.pos.col = y)

  curr_col = 1
  curr_row = 1
  for (i in seq(1, length(gs))){
    ng <- gs[[i]] + add_opts()
    print(ng, vp=vplayout(curr_row,curr_col))
    if (curr_col==ncol){
      curr_col = 1
      curr_row = curr_row + 1
    }else{
      curr_col = curr_col + 1
    }
  }
  if(length(fout) > 0){
    dev.off()
  }
}