Two nodes less than 1 mile apart on the same road fail to work in osmnx.shortest_path_length

Question

I have successfully used osmnx.shortest_path_length to calculate many distances but these two nodes return : NetworkXNoPath: Node 9473072437 not reachable from 178685882.

The node locations were derived from ox.distance.nearest_nodes() and I have verified the the nodes in fact represent the locations I am trying to analyze using openstreetmaps: Node 1

Node 2

As you can see they are quite close to each other. I have tried using simply the network of Sussex County, Delaware, as well as the entire state of Delaware. As expected this change had no impact.

g = ox.graph_from_place('Delaware, USA', network_type="drive")
dst = nx.shortest_path_length(g, source= 178685882, target= 9473072437, weight= 'length')

Answer 1

It's because the only way to access node 9473072437 is via service roads (namely this one), which you are not requesting with the "drive" filter. Use the "drive_service" filter to get all drivable roads including service roads:

import osmnx as ox
G = ox.graph_from_point((38.7776715, -75.3101692), dist=1500, network_type='drive_service')

path = ox.shortest_path(G, 178685882, 9473072437)
print(path)

path = ox.shortest_path(G, 9473072437, 178685882)
print(path)