Hello Pieter,
thanks for the input files.
It seems as the --all-end-follower option would be broken. I set up a
reduced input file for your scenario with only one time slice and
values one can easily understand. What I get when running the setting
with the option set is a distribution:
<routeDistribution id="RWS01_MONIBAS_0671hrr0180ra_0">
<route refId="78878493_to_41875271" probability="0.50"/>
<route refId="78878493_to_43651334" probability="0.50"/>
<route refId="78878493_to_34601778" probability="0.25"/>
<route refId="78878493_to_34600847" probability="0.25"/>
</routeDistribution>
When running the same inputs without setting --all-end-follower, I get:
<routeDistribution id="RWS01_MONIBAS_0671hrr0180ra_0">
<route refId="78878493_to_40790785" probability="0.50"/>
<route refId="78878493_to_44353562" probability="0.25"/>
<route refId="78878493_to_44353583" probability="0.25"/>
</routeDistribution>
What is correct.
Well, this may help for now? If you need the vehicles to be driving to
the end of the road (for being rerouted or whatever), you may use
--arrivalpos -1 (hope this works).
I cannot tell you whether the bug will be fixed, soon. We are quite
busy doing other things - and, as you mentioned, it's an open source
project. You are welcome to contribute.
Sincerely,
Daniel
2014-03-11 14:33 GMT+01:00 Fullerton, Matthew <[email protected]>:
> Dear Pieter,
> A student of mine is investigating these problems and has a good grasp of
> what is going on and what should be improved. Maybe we could talk on Skype in
> the coming days to save on duplicated efforts...
>
> Best,
> Matthew
>
> On 8 Mar 2014 16:50, Pieter Loof <[email protected]> wrote:
> Hello,
>
> I ran some simple tests to see how well DFRouter is able to generate flows
> similar to the real data. So far, I noticed that the flow at source
> detectors is exactly correct, so the vehicles are generated based on the
> source detectors. But when it comes to the distribution of the vehicles
> over available routes, DFRouter can make large errors.
>
> Attached is a picture that I made, which summarizes the output of a test
> scenario. The green detector is a source, the red detectors are sinks. The
> numbers shown at each detector are the number of vehicles that pass in a 3
> hour time period, the top number being the real data measurement and the
> bottom number being the number of vehicles in the simulation.
>
> As you can see, this is a simple problem where one vehicle flow should be
> distributed such that about the right number of vehicles reaches each sink.
> As you can see from the picture, about 1000 vehicles receive the wrong
> route.
>
> I looked into the code to see how DFRouter computes the vehicle
> distribution, but I don't really understand what is happening (I looked at
> the code of RODFNet::buildEdgeFlowMap).
>
> So my questions are:
> 1) Can someone explain to me how DFRouter computes the number of vehicles
> per route?
> 2) How large can the errors become, are there any garantuees under certain
> conditions?
> 3) Will the computation of vehicles per route be improvement in the (near)
> future?
>
> Best regards,
> Pieter
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