I am using an integer variable in DOCPLEX using Python API. I know how to give a range of possible values to these variables using upper bound and lower bound, but how to make sure that the variables take values from only a set of integers?
For eg. I want a variable 'var' to take up values from only the set {-2, -1, 5, 10}. How do I do this?
In https://www.linkedin.com/pulse/making-optimization-simple-python-alex-fleischer/
decision variable in a domain with cplex and cpo
from docplex.mp.model import Model
# Now suppose we can rent only 0,1,3,4 or 5 buses of 40 seats buses
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)
allowedQuantities=[0,1,3,4,5];
mdl.add_constraint(1==sum((a==nbbus40) for a in allowedQuantities))
mdl.solve()
for v in mdl.iter_integer_vars():
print(v," = ",v.solution_value)
"""
which gives
nbBus40 = 3.0
nbBus30 = 6.0
"""
or with cpoptimizer
#Now suppose we can rent only 0,1,3,4 or 5 buses of 40 seats bu
from docplex.cp.model import CpoModel
mdl = CpoModel(name='buses')
nbbus40 = mdl.integer_var(0,1000,name='nbBus40')
nbbus30 = mdl.integer_var(0,1000,name='nbBus30')
mdl.add(nbbus40*40 + nbbus30*30 >= 300)
mdl.minimize(nbbus40*500 + nbbus30*400)
allowedQuantities=[0,1,3,4,5];
nbbus40.set_domain(allowedQuantities)
msol=mdl.solve()
print(msol[nbbus40]," buses 40 seats")
print(msol[nbbus30]," buses 30 seats")
"""
which gives
3 buses 40 seats
6 buses 30 seats
"""
