final int start_id = 1;
List<Integer> partitions = new ArrayList<Integer>();
for (int i = start_id; i <= num_warehouses; i++) {
File path = new File("histograms/" + i + ".hist");
ObjectHistogram h = new ObjectHistogram();
h.load(path, null);
this.histograms.put(i, h);
partitions.add(i);
} // FOR
int num_nodes = 5;