Rutils/maybe-not-useful/nearest.neighbour.r

In manfredo89/ED2io: Manages Input/Output for Ecosystem Demography 2 Model

#==========================================================================================#
#==========================================================================================#
#     This function determines the gridded nearest neighbour for each point of the         #
# network.                                                                                 #
#------------------------------------------------------------------------------------------#
nearest.neighbour = function(netwcoord,gridcoord,g2n=TRUE){
   isok = require(fields)
   if (!isok) stop("The nearest.neighbour function requires the package fields...")

   #---------------------------------------------------------------------------------------#
   #     "Distmat" is the matrix with the distances between the each network point         #
   # (unstructured) and each grid point (structured).                                      #
   #---------------------------------------------------------------------------------------#
   distmat = rdist.earth(x1=netwcoord,x2=gridcoord,miles=FALSE)

   #---------------------------------------------------------------------------------------#
   #    "Nearest" is the index of the closest BRAMS grid point for each point of the       #
   # network.                                                                              #
   #---------------------------------------------------------------------------------------#
   if (g2n){
      nearest = apply(X=distmat,MARGIN=1,FUN=which.min)
   }else{
      nearest = apply(X=distmat,MARGIN=2,FUN=which.min)
   }#end if
   #--------------------------------------------------------------------------------------#

   return(nearest)
}#end function
#==========================================================================================#
#==========================================================================================#