CPO Save Log/Intermediate solutions

Question

I am using the python API of CPO Optimizer. Is there any way to save the log/intermediate highlighted solutions and timestamps to build a chart on the evolution of the optimization?

Thanks in advance!

I haven't found a workaround so far, but copy-pasting the log seems not a feasible way...

Answer 1

If you do not want to rely on callbacks you can also use CPO solution Iterator.

Small changes in https://github.com/AlexFleischerParis/zoodocplex/blob/master/zoocpoenumerate.py

gives

import time
from docplex.cp.model import CpoModel

mdl = CpoModel(name='buses')

nbbus40 = mdl.integer_var(0,6,name='nbBus40')
nbbus30 = mdl.integer_var(0,6,name='nbBus30')
cost= mdl.integer_var(0,1000000,name='cost')

mdl.add(cost==nbbus40*500 + nbbus30*400)
mdl.add(cost<=4000)
mdl.add(nbbus40*40 + nbbus30*30 >= 300)

siter = mdl.start_search(SearchType='DepthFirst',  TimeLimit=100)




for msol in siter:
    print(msol[nbbus40]," buses 40 seats")
    print(msol[nbbus30]," buses 30 seats")
    print("cost = ",msol[cost])
    print("time = ",time.time())
    print("\n")

which gives

3  buses 40 seats
6  buses 30 seats
cost =  3900
time =  1684850008.5023165


 *                      3  0.39s        1         4  = nbBus40
4  buses 40 seats
5  buses 30 seats
cost =  4000
time =  1684850008.6289783


 *                      4  0.51s        1         4 != nbBus40
6  buses 40 seats
2  buses 30 seats
cost =  3800
time =  1684850008.7602491


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 ! Search completed, 3 solutions found.