docs: private HashMap<DensityGrid, CharacteristicVector> adjustForSparseGrid(DensityGrid dg, CharacteristicVector cv, int dgClass)
  	{
  		HashMap<DensityGrid, CharacteristicVector> glNew = new HashMap<DensityGrid, CharacteristicVector>();
  		//System.out.print("Density grid "+dg.toString()+" is adjusted as a sparse grid at time "+this.getCurrTime()+". ");
  		if (dgClass != NO_CLASS)
  		{
  			//System.out.println("It is removed from cluster "+dgClass+".");
  			GridCluster gc = this.cluster_list.get(dgClass);
  			gc.removeGrid(dg);
  			cv.setLabel(NO_CLASS);
  			glNew.put(dg, cv);
  			this.cluster_list.set(dgClass, gc);
  			
  			if(gc.getWeight() > 0.0 && !gc.isConnected())
  				glNew.putAll(recluster(gc));
  		}
  		//else
  			//System.out.println("It was not clustered ("+dgClass+").");
  
  		return glNew;
  	}