get the link map, this is a bit hacky, call for better algorithm
        to place similar nodes together

def get_link_map(self, nslave):
        """
        get the link map, this is a bit hacky, call for better algorithm
        to place similar nodes together
        """
        tree_map, parent_map = self.get_tree(nslave)
        ring_map = self.get_ring(tree_map, parent_map)
        rmap = {0 : 0}
        k = 0
        for i in range(nslave - 1):
            k = ring_map[k][1]
            rmap[k] = i + 1

        ring_map_ = {}
        tree_map_ = {}
        parent_map_ ={}
        for k, v in ring_map.items():
            ring_map_[rmap[k]] = (rmap[v[0]], rmap[v[1]])
        for k, v in tree_map.items():
            tree_map_[rmap[k]] = [rmap[x] for x in v]
        for k, v in parent_map.items():
            if k != 0:
                parent_map_[rmap[k]] = rmap[v]
            else:
                parent_map_[rmap[k]] = -1
        return tree_map_, parent_map_, ring_map_