Igraph 最短路径给出无限值

Question

我正在尝试计算一个节点和两个目标之间的距离，然后比较计算出的路线的长度并将最小的路线保存在列表中。我知道我可以使用 networkx.shortest_path() 但是这个解决方案需要很长时间并且代码需要很长时间才能达到运行。出于这个原因，我选择使用 Igraph。这是代码：

import networkx as nx
import matplotlib.pyplot as plt
import osmnx as ox
import pandas as pd
from shapely.wkt import loads as load_wkt
import numpy as np
import matplotlib.cm as cm
import igraph as ig
import matplotlib as mpl
import random as rd
ox.config(log_console=True, use_cache=True)


city = 'Portugal, Lisbon'
G = ox.graph_from_place(city, network_type='drive')

G_nx = nx.relabel.convert_node_labels_to_integers(G)

ox.speed.add_edge_speeds(G_nx, hwy_speeds=20, fallback=20)

ox.speed.add_edge_travel_times(G_nx)

weight = 'travel_time'

coord_1 = (38.74817825481225, -9.160815118526642)  # Coordenada Hospital Santa Maria
coord_2 = (38.74110711410615, -9.152159572392323)  # Coordenada Hopstial Curry Cabral
coord_3 = (38.7287248180068, -9.139114834357233) # Hospital Dona Estefania
coord_4 = (38.71814053423293, -9.137885476529883) # Hospital Sao Jose 
target_1 = ox.get_nearest_node(G_nx, coord_1)
target_2 = ox.get_nearest_node(G_nx, coord_2)
target_3 = ox.get_nearest_node(G_nx, coord_3)
target_4 = ox.get_nearest_node(G_nx, coord_4)


G_ig = ig.Graph(directed=True)
G_ig.add_vertices(list(G_nx.nodes()))
G_ig.add_edges(list(G_nx.edges()))
G_ig.vs['osmid'] = list(nx.get_node_attributes(G_nx, 'osmid').values())
G_ig.es[weight] = list(nx.get_edge_attributes(G_nx, weight).values())

assert len(G_nx.nodes()) == G_ig.vcount()
assert len(G_nx.edges()) == G_ig.ecount()

route_length=[]
list_nodes=[]

for node in G_nx.nodes:
    length_1 = G_ig.shortest_paths(source=node, target=target_1, weights=weight)[0][0]
    length_2 = G_ig.shortest_paths(source=node, target=target_2, weights=weight)[0][0]

    if length_1<length_2:
        route_length.append(length_1)
    else:
        route_length.append(length_2)
    list_nodes.append(node)

如果您打印包含路线长度的列表，一些值将是 'inf'，这显然没有意义。谁能帮我理解为什么长度会变小？

Answer 1

正如 Vincent Traag 所说 inf 中两个断开连接的节点之间的距离。所以说明对于这样的结果，节点和源头没有连接

Igraph 最短路径给出无限值

Igraph shortest path gives an infinite value

python

networkx

igraph

osmnx