def min_steiner_tree(g, obs_nodes, p=None, return_type='tree', debug=False, verbose=False): assert len(obs_nodes) > 0, 'no terminals' if g.num_vertices() == len(obs_nodes): print('it\'s a minimum spanning tree problem') gc, eweight, r2pred = build_closure(g, obs_nodes, p=p, debug=debug, verbose=verbose) # print('gc', gc) tree_map = min_spanning_tree(gc, eweight, root=None) tree = GraphView(gc, directed=False, efilt=tree_map) tree_edges = set() for e in tree.edges(): u, v = map(int, e) recovered_edges = extract_edges_from_pred(u, v, r2pred[u]) assert recovered_edges, 'empty!' for i, j in recovered_edges: tree_edges.add((i, j)) tree_nodes = list(set(itertools.chain(*tree_edges))) if return_type == 'nodes': return tree_nodes elif return_type == 'edges': return list(map(edge2tuple, tree_edges)) elif return_type == 'tree': vfilt = g.new_vertex_property('bool') vfilt.set_value(False) for n in tree_nodes: vfilt[n] = True efilt = g.new_edge_property('bool') for i, j in tree_edges: efilt[g.edge(i, j)] = 1 subg = GraphView(g, efilt=efilt, vfilt=vfilt, directed=False) if p is not None: weights = subg.new_edge_property('float') for e in subg.edges(): weights[e] = p[e] else: weights = None # remove cycles tree_map = min_spanning_tree(subg, weights, root=None) t = GraphView(g, directed=False, vfilt=vfilt, efilt=tree_map) return t
def min_steiner_tree(g, obs_nodes, debug=False, verbose=False): if g.num_vertices() == len(obs_nodes): print('it\'s a minimum spanning tree problem') gc, eweight, r2pred = build_closure(g, obs_nodes, debug=debug, verbose=verbose) # print('gc', gc) tree_map = min_spanning_tree(gc, eweight, root=None) tree = GraphView(gc, directed=False, efilt=tree_map) tree_edges = set() # print('tree', tree) for e in tree.edges(): u, v = map(int, e) recovered_edges = extract_edges_from_pred(u, v, r2pred[u]) assert recovered_edges, 'empty!' for i, j in recovered_edges: tree_edges.add(((i, j))) tree_nodes = list(set(itertools.chain(*tree_edges))) vfilt = g.new_vertex_property('bool') vfilt.set_value(False) for n in tree_nodes: vfilt[n] = True efilt = g.new_edge_property('bool') for i, j in tree_edges: efilt[g.edge(i, j)] = 1 return GraphView(g, efilt=efilt, vfilt=vfilt)
def get_steiner_tree(g, root, obs_nodes, debug=False, verbose=False): gc, eweight, r2pred = build_closure(g, obs_nodes, debug=debug, verbose=verbose) tree_map = min_spanning_tree(gc, eweight, root=None) tree = GraphView(gc, directed=False, efilt=tree_map) tree_edges = set() for e in tree.edges(): u, v = map(int, e) for i, j in extract_edges_from_pred(g, u, v, r2pred[u]): tree_edges.add((j, i)) # a bit involved... und_tree = edges_to_directed_tree(g, root, tree_edges) return build_minimum_tree(g, root, obs_nodes, extract_edges(und_tree))
def get_steiner_tree(g, root, obs_nodes, debug=False, verbose=False): gc, eweight, r2pred = build_closure(g, obs_nodes, debug=debug, verbose=verbose) tree_map = min_spanning_tree(gc, eweight, root=None) tree = GraphView(gc, directed=False, efilt=tree_map) tree_edges = set() for e in tree.edges(): u, v = map(int, e) for i, j in extract_edges_from_pred(g, u, v, r2pred[u]): tree_edges.add((j, i)) # a bit involved... und_tree = edges_to_directed_tree(g, root, tree_edges) return build_minimum_tree(g, root, obs_nodes, extract_edges(und_tree))