OSMNX Shortest Path - How to skip node if not reachable and take the next nearest

Question

I am using the OSMNX library on python. I am creating a 'drive' street network from a coordinate point I am setting the parameter 'retain_all' to False (I am assuming it should only bring connected nodes) However when i am running the shortest path function, i get the error "Node 7079214188 not reachable from 5636337791"

I know i can use 'try' and 'except' but i am looking for a way to adjust the shortest path function and skip to next nearest node that can be reachable.

Kindly find below the code to reproduce the problem :

import networkx as nx
import osmnx as ox
import plotly.graph_objects as go
import numpy as np

RDC_Coordinates = (27.4757976,-82.4192142)
X = ox.graph_from_point(RDC_Coordinates,distance=32186,network_type='drive',retain_all=False)
#Plot map
#fig, ax = ox.plot_graph(X)


# define origin and desination locations 
origin_point = (27.4289, -82.388)  #Blue Runner
destination_point = (27.476, -82.4192)   # Terracota

# get the nearest network node to each point
orig_node = ox.get_nearest_node(X, origin_point)
dest_node = ox.get_nearest_node(X, destination_point)

# how long is our route in miles?
nx.shortest_path_length(X, orig_node, dest_node, weight='length')/1609

Answer 1

Your graph is weakly connected. Thus, some nodes may be unreachable from certain other nodes. Here are a couple of options. 1, you could copy your graph and recursively remove unsolvable origins/destinations from it until you get a solvable path. 2, you could use a strongly connected graph instead.

import networkx as nx
import osmnx as ox
ox.config(use_cache=True, log_console=True)

center_point = (27.4757976, -82.4192142)
orig_point = (27.4289, -82.388)
dest_point = (27.476, -82.4192)
G = ox.graph_from_point(center_point, dist=1000, network_type='drive', retain_all=False)

# FAILS due to unsolvable path
orig_node = ox.get_nearest_node(G, orig_point)
dest_node = ox.get_nearest_node(G, dest_point)
nx.shortest_path_length(G, orig_node, dest_node, weight='length')

# OPTION 1: recursively remove unsolvable origin/destination nodes and re-try
G2 = G.copy()
solved = False
while not solved:
    try:
        orig_node = ox.get_nearest_node(G2, orig_point)
        dest_node = ox.get_nearest_node(G2, dest_point)
        print(nx.shortest_path_length(G2, orig_node, dest_node, weight='length'))
        solved = True
    except nx.exception.NetworkXNoPath:
        G2.remove_nodes_from([orig_node, dest_node])
    
# OPTION 2: use a strongly (instead of weakly) connected graph
Gs = ox.utils_graph.get_largest_component(G, strongly=True)
orig_node = ox.get_nearest_node(Gs, orig_point)
dest_node = ox.get_nearest_node(Gs, dest_point)
nx.shortest_path_length(Gs, orig_node, dest_node, weight='length')