Multiple plot function. ggplot objects can be passed in ..., or to plotlist (as a list of ggplot objects)
multiplot(..., plotlist = NULL, cols = 1, layout = NULL)a sequence of ggplots to be plotted in the grid.
a list containing ggplots as elements.
number of columns in layout
a matrix specifying the layout. If present, 'cols' is ignored. If the layout is something like matrix(c(1,2,3,3), nrow=2, byrow=TRUE), then plot 1 will go in the upper left, 2 will go in the upper right, and 3 will go all the way across the bottom. Taken from R Cookbook
A ggplot containing the plots passed as arguments