Skip to main content
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [List Home]
Re: [sumo-user] Different vehicle behavior in same surroundings
Hello Jakob,

Given the following from the link you pointed out:

"This random number generator (RNG) is initialized with a seed value which defaults to the (arbitrary) value 23423. 
This setup makes all applications deterministic by default as the sequence of random numbers is fixed for a given seed. 
The seed may be changed using the option --seed <INT>. When using the option --random the seed will be chosen based on the current system time resulting in truly random behavior."

I have two questions:

First, I had the seed set to this: seed = np.random.randint(10000), so the deterministic, totally reproducible behavior in certain settings, shouldn't be expected. 
Second, even if I hadn't chosen a random one, and let it to the default 23423 stated above instead, I still don't get why this is fixed for always when I run scenario A, and then B at once, and results in always the same behavior, but it is different when I run only scenario B over and over, to get always the same behavior, but different than the one in A.

(1. Run A than reset Sumo (not restart), then run B ---> no matter how often I run this I get exactly the same behavior,
 2. Run B ---> no matter how often I run this I get exactly the same behavior but slightly different than the one in scenario B in 1.)


To me this two make sense:

 either I get the same behavior whenever I run scenario B regardless if I run it on its own or before/after other scenarios, or I always(or sometimes) get a slightly different ones due to a random seed (but also within runs of A,B or just B).

Can you please explain what am I missing here?

Thanks!

VG
Branka



Am Dienstag, 14. April 2020, 07:58:18 MESZ hat Jakob Erdmann <namdre.sumo@xxxxxxxxx> Folgendes geschrieben:


By default the random seed is fixed to achieve the reproducible behavior you already noticed (as explained at https://sumo.dlr.de/docs/Simulation/Randomness.html#random_number_generation_rng).

Am Mo., 13. Apr. 2020 um 23:58 Uhr schrieb Branka Mircevska <brankamircevska@xxxxxxxxx>:
Hey Jakob,

thanks for the reply!

I was assuming it has to do something with the seed, and random init of vehicle parameters. 
However, my confusion comes from the fact that if I run scenario 20 only, N number of times, the behavior is always the same (even though there should be randomness here as well if I am not mistaken?!).
Similarly, when I run scenario 20 after scenario 10, N number of times, I get the same results all N times.

Does this make sense?

(Note that I set both, the starting speed and the starting position of the vehicles, to a specific value, not to randomly chosen one.)

Thanks!

VG
Branka 



Am Montag, 13. April 2020, 22:36:07 MESZ hat Jakob Erdmann <namdre.sumo@xxxxxxxxx> Folgendes geschrieben:


The sumo-controlled vehicles are using the default model with stochastic components. This will result in divergent vehicle behavior when running a different simulation sequence with a different number / ordering of random number generator calls. For details, see https://sumo.dlr.de/docs/Simulation/Randomness.html

regards,
Jakob

Am Mo., 13. Apr. 2020 um 15:08 Uhr schrieb Branka Mirchevska <brankamircevska@xxxxxxxxx>:
Hello,

I'm trying to run 2 predefined Sumo scenarios one after the other (scenario
ids 10_0, and 20_0).
They contain 10 and 20 Sumo controlled vehicles each, and I place my
remotely controlled vehicle at a certain position in both to drive among
them.
The problem is the following:
when I run scenario 10 and then scenario 20 after it, the behavior is
different than when I run scenario 20 right away.

here is a demonstration:

Only scenario 20_0:
_________________________________


Scenario ID:  20_0
----------------------------------------  time-step:  0
EGO lane pos and speed                   :  100.0 ,   8.0
x, y, angle, speed for EGO to execute:  101.530884567 5.19671627088
90.7360694615 8.10524126657
HUMAN_19 lane position and speed  :  121.0 10.0
----------------------------------------  time-step:  1
EGO lane pos and speed                   :  101.530884567 ,   8.10524126657
x, y, angle, speed for EGO to execute:  103.100752622 5.1765673393
91.6889555588 8.39699835768
HUMAN_19 lane position and speed :  123.054754372 10.2737718593
----------------------------------------  time-step:  2
              ...


First scenario 10_0 and then 20_0:
__________________________________

Scenario ID:  20_0
----------------------------------------  time-step:  0
EGO lane pos and speed                   :  100.0 ,   8.0
x, y, angle, speed for EGO to execute:  101.530884567 5.19671627088
90.7360694615 8.10524126657
HUMAN_19 lane position and speed :  121.0 10.0
----------------------------------------  time-step:  1
EGO lane pos and speed                   :  101.530884567 ,   8.10524126657
x, y, angle, speed for EGO to execute:  103.100752622 5.1765673393
91.6889555588 8.39699835768
HUMAN_19 lane position and speed  :  123.093816682 10.4690834098
----------------------------------------  time-step:  2
              …

You can see that the behavior of HUMAN_19 is slightly different in time-step
1 event though EGO doesn’t change its remote control parameters.

I have included a small example in the .zip folder attached. If you run:

python2.7 small_example/src/run_scenario.py,

first scenario 10_0 then scenario 20_0 will be executed, one after another.

If you comment in line 63 (#scenario_ids = ['20_0']) in run_example.py, only
scenario 20_0 will be executed.

After running the two options, you will be able to see the above output,
where in time-step 1 ‘HUMAN_19’ behaves differently even though the
environment is exactly the same.

Do you have any clue why?

Thanks!

Best,
Branka

small_example.zip
<http://sumo-user-mailing-list.90755.n8.nabble.com/file/t361/small_example.zip> 




--
Sent from: http://sumo-user-mailing-list.90755.n8.nabble.com/
_______________________________________________
sumo-user mailing list
sumo-user@xxxxxxxxxxx
To unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/sumo-user
_______________________________________________
sumo-user mailing list
sumo-user@xxxxxxxxxxx
To unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/sumo-user
_______________________________________________
sumo-user mailing list
sumo-user@xxxxxxxxxxx
To unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/sumo-user
_______________________________________________
sumo-user mailing list
sumo-user@xxxxxxxxxxx
To unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/sumo-user

Back to the top