I have a waterline dataset (.shp) where I have been using Shortest Path (Point to Point) analysis in QGIS 3.16. Using QGIS, I have found that if I do not increase the Topology tolerance parameter in the Shortest Path window I get the error: "There is no route from start point to end point.". However, if I adjust the Topology tolerance up by 1' I can get the correct path.

When I perform the same analysis in NetworkX I think I am encountering a similar issue. Where I will get an error like:

NetworkXNoPath: No path between (-121.16730791899134, 44.292191414768645) and (-121.17873042113929, 44.263451141699434)

even though I have performed this analysis successfully in QGIS.

Does NetworkX have a parameter that can increase the detectable edge of a node?

Example of successful Shortest Path in QGIS that NetworkX is unable to id correctly:

enter image description here

  • 1
    In QGIS: "Snap geometries to layer". Snap it to itself
    – BERA
    Feb 15, 2022 at 7:33
  • I was hoping to get some insight into NetworkX, but thank you!
    – Derek_P
    Feb 15, 2022 at 19:12

1 Answer 1


I have the same problem, and used snap geometries to layer set the input and reference to itself. You have to use the cleanest line you'll ever used in terms of topology.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.