Not implemented function 'delay'

[CarineAVieira]

The function delay is not implemented on pysd...
Is there a way to come around this problem?

[enekomartinmartinez]

Hi @CarineAVieira

Thank you for opening the PR! You mean the delay function from XMILE or any other kind of delay?

It seems that the workflow of that function is the same as Vensin's DelayFixed.

If that is so, it will be very easy to modify the translation process to make it work. However, I would ask you if you can provide an XMILE test model with some examples of that function and the output that produces, to check that everything works as should in PySD. I cannot do it because I currently don't have Stella or Vensim working. You can replicate this model with Stella https://github.com/SDXorg/test-models/tree/master/tests/delay_fixed

[CarineAVieira]

Hi @enekomartinmartinez ,

Yes, I meant the DELAY function of XMILE...
I don't understand vensin very well, but this is an example of the function that does not work on PySD.
The error: "NotImplementedError: Not implemented function 'delay'"

Equations:
Stock_1(t) = Stock_1(t - dt) + (Flow_2) * dt
INIT Stock_1 = 100
INFLOWS:
Flow_2 = Converter_1*Stock_1
Converter_1 = 0,02
Converter_2 = (((Stock_1/DELAY(Stock_1; 1))-1)*100)

The exemple you asked for:
https://drive.google.com/file/d/175wF5660xJf0f9OAyn1MNXBhnzejhkSm/view?usp=sharing

Thank you :)

[enekomartinmartinez]

Thank you @CarineAVieira

Could you also please provide the output that this model produces, a .csv o .tab file would work

Here is explained how to do it to make it comparable with our test-suite https://github.com/SDXorg/test-models#result-formatting

[CarineAVieira]

@enekomartinmartinez here the file:https://docs.google.com/spreadsheets/d/1FAB9LsVHRCf7pZTsXwaHZ8VCRcdG-cYq/edit?usp=sharing&ouid=110156770447253975490&rtpof=true&sd=true

Thanks :)

[enekomartinmartinez]

Hi @CarineAVieira it is already solved in version 3.13.2. It should be already available in PyPI and in some hours in conda-forge.

Note that some of the functions implemented in XMILE are not tested as we miss XMILE users currently, it would be nice if you could provide sample test for any of them.

[CarineAVieira]

Hi @enekomartinmartinez, thank you very much!

I can provide some samples of some functions that are not tested.
How can I do? Send a sample and the output ?

[enekomartinmartinez]

If you prefer, you can open a pull request in the test-models repo. You can look at some examples inside the tests folder. In some cases, you could simply replicate some existing Vensim models with Stella.

For example, this model is only in Vensim and includes some functions that are not tested with XMILE (STEP, DELAYN), in this case, reproducing the same model with Stella will be enough as we would expect the same outputs
https://github.com/SDXorg/test-models/blob/master/tests/delay_pipeline/test_pipeline_delays.mdl

It can be done similarly for some other models. In some cases, creating a new folder with the new model and outputs may be necessary as it may not be there. Note that some parameters could change their order in Stella compared to Vensim, but generally, the functions have the same name.

If you prefer to simply send me the model with the output as done with the previous one, this will also be useful. However, I would prefer to reuse existing models.

Any help will be very useful as the XMILE translator is not fully tested, which could lead to bugs.