[Qgis-user] help with shortest-path/network analysis (multiple origins to multiple destinations)

Sat May 7 06:48:15 PDT 2022

Thank you Ujaval,

I'll try this as well. Would you suggest to run it like a batch process on
all origin-destination pairs, as the one suggested at point 22 of the
tutorial?

Thanks a lot again and have a good weekend!
Francesca

Il giorno ven 6 mag 2022 alle ore 16:47 Ujaval Gandhi <
ujaval at spatialthoughts.com> ha scritto:

> You need to do Distance Matrix. See
> https://www.qgistutorials.com/en/docs/3/origin_destination_matrix.html
>
> On Fri, 6 May 2022 at 7:33 PM, Francesca Parente via Qgis-user <
> qgis-user at lists.osgeo.org> wrote:
>
>> Thank you very much indeed Nicolas, for your inputs and all the suggested
>> materials!
>> I have 50 targets and 532 origins. My goal is to define where is best to
>> go within the 50 destinations for each starting point - given the actual
>> range of choices though, so I'm not sure that running a batch one-to-many
>> would take into account all the variables properly as a many-to-many would
>> do. In the absence of a specific modelling, also some second best could
>> work.
>>
>> I understand that your upstream-downstream-Dijkstra script is suitable
>> for layer-to-layer indeed and I'm trying to run it, but at the >>> import
>> geopandas as gpd<< line I got the following error message:
>>
>>
>>
>>
>>
>>
>>
>> *Traceback (most recent call last):  File
>> "C:\OSGEO4~1\apps\Python37\lib\code.py", line 90, in runcode    exec(code,
>> self.locals)  File "<input>", line 1, in <module>  File
>> "C:/OSGEO4~1/apps/qgis/./python\qgis\utils.py", line 799, in _import    mod
>> = _builtin_import(name, globals, locals, fromlist, level)*
>> *ModuleNotFoundError: No module named 'geopandas'*
>>
>> I've been following your tutorial, but I admit I'm not quite familiar
>> with py. I've gone through the remaining import coding and it seems
>> working, but I'm not sure the "geopandas" module is needed or not to
>> properly complete the script.
>>
>> Thanks again!!
>> Best,
>> Francesca
>>
>> Il giorno gio 5 mag 2022 alle ore 22:28 Nicolas Cadieux <
>> njacadieux.gitlab at gmail.com> ha scritto:
>>
>>> Hi,
>>>
>>> How many shortest path calculations are you looking at? You could
>>> probably do a all pairs shortest path dijkstra and filter the results.  You
>>> could batch multiple one to many (point to layers)  In QGIS using the
>>> processing plug-in.
>>>
>>> I did create an algorithm using networkX that could be modified to work
>>> with two input layers.  This could be useful if QGIS is not fast enough or
>>> if you have too many routes to calculate.  You will find it in the links
>>> below. Keep in mind this algorithm was for rivers therefore you have no
>>> trafic rules.  This would need more work.
>>>
>>> You will also find an article we wrote in Data that may help.  If you
>>> have trouble with the network, look in the QGIS hub for the models. Look
>>> for the 3 “fix directional networks models”.
>>>
>>> I added a few YouTube videos I made.
>>>
>>> https://gitlab.com/njacadieux/upstream_downstream_shortests_path_dijkstra
>>>   <https://www.mdpi.com/2306-5729/5/1/8>
>>>
>>> https://www.mdpi.com/2306-5729/5/1/8
>>>
>>> https://plugins.qgis.org/models/
>>>
>>> https://youtu.be/v61PafSByvM
>>>
>>> https://youtu.be/qQrHcKtmr3o
>>>
>>>
>>> Nicolas Cadieux
>>> https://gitlab.com/njacadieux
>>>
>>> Le 5 mai 2022 à 10:38, Francesca Parente via Qgis-user <
>>> qgis-user at lists.osgeo.org> a écrit :
>>>
>>> 
>>> Hello everyone,
>>>
>>> I'd need to identify optimal destinations (within a point layer of
>>> geolocated facilities) for each territory of a given set of possible
>>> origins.
>>> I already calculated a distance matrix between the two point-layers, and
>>> also applied the distance-to-nearest-hub tool to generate a string layer
>>> and identify the optimal facilities.
>>> But I'd like to obtain a more realistic estimate, accounting for the
>>> roads network (and ideally their travel times). With quite a few issues, I
>>> finally managed to import an OSM road network from download.geofabrik.de
>>> (in order to cover my area of interest, I had to merge two different
>>> vectors fo Center and Southern Italy and then extract a focus spot in
>>> between the two and save it as a lighter layer, otherwise it also took an
>>> eternity to run every analysis).
>>>
>>> So now my question would be: is there a tool to perform a layer-to-layer
>>> shortest-path analysis that takes it into account?
>>> All that I could find was either point-to-point or
>>> layer-to-point/point-to-layer (I looked also at built-in network analysis
>>> tool and Qneat3 plugin).
>>>
>>> Any kind of inputs and suggestions will be more than welcome!
>>> Thanks a lot for your support and have a good day,
>>> Francesca
>>>
>>> --
>>> ----------------------------
>>> Francesca Parente
>>>
>>> _ SESS Euro PhD
>>> <https://phd.uniroma1.it/web/FRANCESCA-PARENTE_nT1602922_IT.aspx> in
>>> SocioEconomic and Statistical Studies
>>> _ Luiss SEP <https://sep.luiss.it/> School of European Political Economy
>>>
>>>
>>> email: francescaparente.rse at gmail.com
>>>        parentef at luiss.it
>>>
>>> _______________________________________________
>>> Qgis-user mailing list
>>> Qgis-user at lists.osgeo.org
>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>
>>>
>>
>>
>> _______________________________________________
>> Qgis-user mailing list
>> Qgis-user at lists.osgeo.org
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>
> --
> [image: Logo] <https://spatialthoughts.com/>
> Ujaval Gandhi
> Spatial Thoughts
> mobile: +91-8095684687
> email: ujaval at spatialthoughts.com
> [image: LinkedIn icon] <https://www.linkedin.com/in/spatialthoughts/>  [image:
> Twitter icon] <https://twitter.com/spatialthoughts>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20220507/a87e7bec/attachment.htm>