ampl.readData(filename): TypeError: basic_string

[Xavier RIXHON]

Hello,

When I set up my ampl problem, I encounter an issue reading one specific file called "PESTD_data_decom_allowed.dat" (all the other files seem to be read flawlessly). Here is the error that comes out:

File "/Users/xrixhon/.pyenv/versions/3.7.6/lib/python3.7/site-packages/amplpy/ampl.py", line 559, in readData
self._impl.readData(filename)

TypeError: basic_string

I searched through the source code of amplpy but couldn't figure it out. Could you please help me?

To be exhaustive, here are the kind of lines written in the file:

let decom_allowed ['2015_2020' , '2010_2015' , 'NUCLEAR'] := 1;

Thanks in advance,

Best regards,

Xavier

[Filipe Brandao]

Hi Xavier,

That error comes for the underlying C++ API. Instead of ampl.readData(filename), could you please try ampl.readData(str(filename))?

Best regards,
Filipe

[Xavier RIXHON]

Hello Filipe,

Unfortunately, it does not work much better. I'm not sure it comes from the name of the file as, if I comment all the lines of the .dat file, it is read properly. It should come from what's written in the file (like : let decom_allowed ['2015_2020' , '2010_2015' , 'NUCLEAR'] := 1;) but I don't know what it could be exactly and how to solve this?

If you have any other idea, I'd be glad to read and try it.

Thanks for your help,

Best regards,

Xavier

[Filipe Brandao]

Hi Xavier,

Sorry, I had not noticed the "let" in "let decom_allowed ['2015_2020' , '2010_2015' , 'NUCLEAR'] := 1;". "let" commands are part of models, not data. You can see the data format at https://ampl.com/BOOK/CHAPTERS/12-data.pdf. Instead of ampl.readData('PESTD_data_decom_allowed.dat'), could you please try ampl.read('PESTD_data_decom_allowed.dat')?

[Xavier RIXHON]

Hello Filipe,

Once again it is not the issue :s. Strangely, I've been able to run my code previously with a similar file but from now on, I've got this bug "out of nowhere"? Would you have any other idea to figure it out?

Thanks in advance for your quick response and your support,

Best regards,

Xavier

[Filipe Brandao]

Hi Xavier,

Could you please send all the files necessary to reproduce this issue to [e-mail]?

If that is not possible, you can add the following right after instantiating the AMPL object:

ampl._startRecording('session.log')
ampl.setOption('_log_input_only', False)

This will produce a file session.log that should show what happened right before the exception was thrown.

[Xavier RIXHON]

Hello Filipe,

Thank you so much for your help. Generating the log helped to identify what was the issue. I was allocating the PESTD_data_decom_allowed.dat file before instantiating the parameter used in this file. It resulted in this no-clue-giving error TypeError: basic_string whereas the log file helped to identify the actual issue.

Thanks again for your help and your support,

Best regards,

Xavier