[Qgis-user] Shortest path (Network Analysis)

[Paul Wittle]

Hi,

I've also been investigating this sort of work over the last two weeks and have largely come to the same conclusion. I don't think there is a way to do it directly at present without a chargeable plugin but I can't help but feel that it might be possible to create a processing toolbox script which achieves traveling sales using the tools available. QNEAT3 allows you to create a distance matrix and it is not difficult to merge two point layers to get a matrix with the required information. Once you have a distance matrix then in theory there should be algorithms / documented methods somewhere by which we can extract an optimal route order from the results.

That said, I've not had the time to look at this myself and of bigger concern is the lack of support for turn restrictions in the default routing tools. This means that the standard QGIS tools (and I assume QNEAT3 although I've not really looked at Networks) will be jumping off bridges and recommending banned turns.

It would be interesting to know if any of the stuff I've mentioned above is being looked at as I might be interested in working with others to develop some improvements at some point; subject to finding time and employer approval.

Sorry I can't be more helpful but perhaps it will give you a manual method in the short term,
Paul

https://www.jstor.org/stable/167205?seq=1#page_scan_tab_contents (example academic paper)

Message: 2
Date: Fri, 4 Oct 2019 13:59:36 +0000
From: "Tsering W. Shawa" <shawatw at princeton.edu>
To: "qgis-user at lists.osgeo.org" <qgis-user at lists.osgeo.org>
Subject: [Qgis-user] Shortest path (Network Analysis)
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I am trying to find a tool in QGIS that will allow me to calculate shortest path between two layers (number of hospitals to number of addresses) using road network data. There are two plugins (Networks and QNEAT3) and Network analysis tools in Processing Toolbox but none of them allow me to calculate shortest path between two layers. Either the tools will allow me to find the shortest route between a layer (multiple locations) to a single location by picking interactively an origin or a destination location or interactively picking one an origin and a destination location. However, none of the tools will allow a person to upload or select two layers that has multiple point locations to calculate the shortest path.

Any recommendation for tools to solve my problem?

Thanks,
-Wangyal


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