How to export docplex solutions in Python?

Question

I use docplex.model.print_solution() to get solutions in the console. How can I export all the solutions to a file?

Thanks

Answer 1

You can use python files.

Let me use the zoo example.

from docplex.mp.model import Model

mdl = Model(name='buses')
nbbus40 = mdl.integer_var(name='nbBus40')
nbbus30 = mdl.integer_var(name='nbBus30')
mdl.add_constraint(nbbus40*40 + nbbus30*30 >= 300, 'kids')
mdl.minimize(nbbus40*500 + nbbus30*400)
mdl.solve(log_output=True,)

#display solution
for v in mdl.iter_integer_vars():
    print(v," = ",v.solution_value)

#write solution to a file
f= open("c://temp//sol.txt", "w")
for v in mdl.iter_integer_vars():
    f.write(str(v)+" = "+str(v.solution_value)+'\n')
f.close()

"""

which gives

nbBus40  =  6.0
nbBus30  =  2.0

in the display and in the file

"""

from https://github.com/AlexFleischerParis/zoodocplex/blob/master/zoowritesolutioninafile.py

Answer 2

The export method will create a detailed json file:

mdl.solution.export("solution.json")

If you want to store only the results you see in docplex.model.print_solution(), you can use:

with open("solution.txt", "w") as solfile:
    solfile.write(mdl.solution.to_string())