Read/Write model files in .opb format

[AlbertZhangHIT]

Hi there, I have many model files in .opb format. How could I translate these files into .mps/.lp format so that python-mip could solve it ? Moreover, is there a way to translate the .mps/.lp format model file into .opb format?

[sebheger]

Hi @AlbertZhangHIT,

I have never heard about .opd file extension before. .opd files are not supported by python-mip. But gurobi supports it. With a pip installed gurobipy you could read the .opd and then write it as .lp/.mps without solving it.

[AlbertZhangHIT]

Thanks a lot, it really solves my problem!

[AlbertZhangHIT]

Hi @sebheger ,

I got a really weird problem when using gurobipy.
I saved my model which has N variables into .opb format file with the help of gurobipy. But when I loaded the model back from the .opb format file using gurobipy, I found that the number of variables changed to N-1.
It is really weird.

Update:
I have solved this problem. There may be some bug in writing out .opb model in gurobipy. It always write variable x1000 as
x100.