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pythoncplex

CPLEX program with absolute values in Python

I need to write a PL in python and solve it with CPLEX library but i'm a beginner and therefore i don't know how to write it in Python.

The program is:

MIN ΣΣ abs(Ui - Uj)        with i = 1, j = i + 1
subject to:
    Ui = Σ Wj * Xji        ∀i
    Xji is 0/1 integer     ∀i,j with i < j
    0.0 =< Ui <= T
Solution

  • abs is very easy to use with docplex.

    Let me change a bit the zoo example to use abs

    Suppose I want to get as close as possible to cost 3900

    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(mdl.abs(nbbus40*500 + nbbus30*400-3900))

mdl.solve()

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