How to create a Processing script using the shortest path algorithm?

Question

I'm currently using the Road Graph plugin to find the shortest path in a road network - however, I'd like to put this to a processing script (to be used in a model later) and the Road Graph Plugin has no API to be used in a model.

Is there a way to put the shortest path algorithm to a processing script and then use this script in a model?

I found some python scripts for networks/shortest path in the Python Cookbook and tried to put it to a processing script - but as I am a complete newbie with python I didn't get far..

The script should:

• Take a roadnetwork (blue) and and a line vector layer (violet) as input
• Put the start (green) - and endpoint (red) of the line as start and end of the path to be claculated
• Use the intersections of the input line and the network as waypoints, that the path should follow
• Find the shortest path (red ribbon) by routing through the network and save the path as vector layer

Can anybody help me with this script?

Answer 1

You can find multiple versions of routing scripts which use the QGIS network analysis library in my Github repository, e.g. https://github.com/anitagraser/QGIS-Processing-tools/blob/master/2.2/scripts/point_layer_to_route.py which converts an ordered set of points into a route.

None of the scripts use the intersections of an input line with the network. That's something you will have to add on your own.