如何使用graph-tool (使用Dijkstra算法)求出源到最大距离内所有点的距离

from graph_tool.all import *

def find_nodes_within_distance(graph, source, max_distance):
    dist_map = shortest_distance(graph, source)
    nodes_within_distance = [v for v, dist in enumerate(dist_map.a) if dist <= max_distance]
    distances = [dist_map[v] for v in nodes_within_distance]
    return nodes_within_distance, distances

# 创建有向图对象
graph = Graph(directed=True)

# 添加节点和边
v1 = graph.add_vertex()
v2 = graph.add_vertex()
v3 = graph.add_vertex()
v4 = graph.add_vertex()
e1 = graph.add_edge(v1, v2)
e2 = graph.add_edge(v2, v3)
e3 = graph.add_edge(v3, v4)

# 求解源节点到最大距离内的节点和距离
source = v1  # 源节点索引
max_distance = 2  # 最大距离阈值
nodes, distances = find_nodes_within_distance(graph, source, max_distance)

# 输出结果
for node, distance in zip(nodes, distances):
    print(f"节点 {node} 距离源节点的距离为 {distance}")