Hello,
The routing device is not randomized (at leas by default, but there is an
option for that). Instead it constantly updates travel times using current
speeds and then averaging. Since those speeds fluctuate from second to
second, fastest routes fluctuate as well. DUROUTER on the other hand uses
the speed limits by default. If you load weights for DUAROUTER it uses
these weights according to their time resolution. By setting suitable
configuration parameters, you can get the routing device to behave like
DUAROUTER (i.e. not updating travel times).

regards,
Jakob

2016-10-13 15:58 GMT+02:00 Iris Bekker <iris.bek...@braindrops.nl>:

> Hi Jakob,
>
> Thank you for your tips. I have looked both at the routing using devices
> and duarouter. Is my assumption that the devices use a randomized dijkstra
> correct? Or do they spread out over the different routes in a different
> manner. I also have some questions regarding DUAROUTER, but should I start
> a new threat for that?
>
> My goal is to compare routing with a shortest-path (or quickest-path)
> algorithm, where a car just picks the route best for itself, with routing
> using some real time centralized router which should aim at decreasing the
> global travel time. At least, that was the idea I had when I started...
> Making a smart router looks more difficult by the second.
>
> Kind regards,
> Iris
>
>
>
> On 10/10/16 13:44, Jakob Erdmann wrote:
>
> Hello,
> - changeTarget uses the router configured with --routing-algorithm, that
> one is not randomized. it uses travelTime. The travel times obtained as
> described here: http://sumo.dlr.de/wiki/Simulation/Routing#Travel-
> time_values_for_routing
> - rerouteTravelTime() works the same way but uses the current travelTimes
> (without any smoothing)
> - rerouteEffort() is currently broken (http://sumo.dlr.de/trac.wsgi/
> ticket/2580)
>
> For automatic routing I highly recommend this: http://sumo.dlr.de/wiki/
> Demand/Automatic_Routing.
>
> regards,
> Jakob
>
>
> 2016-10-07 17:51 GMT+02:00 Iris Bekker <iris.bek...@braindrops.nl>:
>
>> Dear SUMO list,
>>
>> I am still busy with setting up some experiments with routing traffic.
>> Originally I intended to do all the route-calculations myself, and then
>> assign the new routes to vehicles using traci. However, SUMO also
>> supports its own rerouting. Time to investigate!
>>
>> As usual, I find myself getting stuck with details. So let's start:
>> changeTarget(self, vehID, edgeID) reroutes the car to the chosen edge. I
>> belief the routing algorithm used is the one selected with the
>> --routing-algorithm option when initializing SUMO? Is it true that the
>> Dijkstra's algorithm being used is not randomized? And does this reroute
>> use distance or expected travel times?
>>
>> Second, I wonder about rerouteTravelTime() and rerouteEffort(). The
>> latter reroutes based on the amount of energy is required to finish the
>> route I presume? Do I understand correctly that rerouteTravelTime() on a
>> car traveling from A to B should give the same result as calling
>> changeTarget() on a car standing at A heading to B?
>>
>> Also, is there a way of having a car automatically using the routing
>> algorithm when it gets added? Right now, I intend to use
>> traci.vehicle.addFull(vehID, "ID of edge car is currently on", ...) and
>> then changeTarget() to get this behaviour.
>>
>> I expect that having SUMO do the routing will be quicker than calling
>> all the edge's adapted travel times through traci, finding a route, and
>> then sending that back through traci. However, I will try and run some
>> benchmarks in the near future. Also, I am interested in how SUMO
>> calculates the adapted travel time of an edge, though I expect I can
>> find this on the wiki if I look for it more thoroughly.
>>
>> As always, thank you very much for all your help,
>>
>> Iris Bekker
>>
>>
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>
>
>
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