01logit_simul.py: Warning chosen alternative not available

[Jason Hawkins]

I am running the 01logit_simul for Python Biogeme with Pandas. It gives me the message:  

WARNING  [biogeme.py:140] The chosen alternative is not available for the following observations (rownumber[choice]): 9[3]-10[3]-11[3]-12[3]-13[3]-14[3] ...

There is no warning when running 01logit.py. I checked the database and alt3 (car) is not available for these observations, but the chosen alternative is alt2 (SM). Perhaps there is an off-by-1 error in the simulate code somewhere? I had a look through the source but couldn't find anything out of place.

Thanks,

Jason

[Michel Bierlaire]

Because the model is applied to all alternatives for all observations, irrespectively of their availability. 

prob1 = models.logit(V,av,1)

prob2 = models.logit(V,av,2)

prob3 = models.logit(V,av,3)

The warning can be ignored as the probability is 0. 

In the 01logit, the model is calculated for the chosen alternative only, which, in principle, is always available. 

logprob = bioLogLogit(V,av,CHOICE)

In the future, I plan to include parameters to turn off the warnings. But it is not available now. 

Michel

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