R/process_get_arrangement.R

In tmap: Thematic Maps

process_get_arrangement <- function(nx, asp_ratio) {
	#           asp ~ nrow      
	#       |-------------- 
	#   1   |
	# ~ncol |       nx
	#       | 
	ncol_init <- sqrt(nx/asp_ratio)
	nrow_init <- nx / ncol_init
	
	# rounding:
	nrow_ceiling <- min(ceiling(nrow_init), nx)
	ncol_ceiling <- min(ceiling(ncol_init), nx)
	
	# find minimal change
	nrow_xtra <- abs(nrow_ceiling - nrow_init) * ncol_init
	ncol_xtra <- abs(ncol_ceiling - ncol_init) * nrow_init
	
	# calculaet the other, and subtract 1 when possible
	if (nrow_xtra < ncol_xtra) {
		nrow <- nrow_ceiling
		ncol <- ceiling(nx / nrow)
		if ((nrow-1) * ncol >= nx) nrow <- nrow - 1
	} else {
		ncol <- ncol_ceiling
		nrow <- ceiling(nx / ncol)
		if ((ncol-1) * nrow >= nx) ncol <- ncol - 1
	}
	c(nrow=nrow, ncol=ncol)
}