 FICO Xpress Optimization Examples Repository
 FICO Optimization Community FICO Xpress Optimization Home   Basic MIP tasks: binary variables; logic constraints

Description
We wish to choose among items of different value and weight those that result in the maximum total value for a given weight limit.

Further explanation of this example: 'Xpress Python Reference Manual'

Source Files
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Data Files

burglar.py

'''*******************************************************
* Python Example Problems                             *
*                                                     *
* file burglar.py                                     *
* Example for the use of the Python language          *
* (Burglar problem)                                   *
*                                                     *
* (c) 2018-2023 Fair Isaac Corporation                *
*******************************************************'''

from __future__ import print_function
import xpress as xp

Items = range(8)

WTMAX = 102  # Max weight allowed for haul

x = [xp.var(vartype=xp.binary) for _ in Items]

p = xp.problem()

VALUE = [15, 100, 90, 60, 40, 15, 10, 1]
WEIGHT = [2, 20, 20, 30, 40, 30, 60, 10]

# Objective: maximize total value
p.setObjective(xp.Sum(VALUE[i]*x[i] for i in Items),
sense=xp.maximize)

# Weight restriction
p.addConstraint(xp.Sum(WEIGHT[i]*x[i] for i in Items) <= WTMAX)

p.optimize()           # Solve the MIP-problem

# Print out the solution
print("Solution:\n Objective: ", p.getObjVal())
for i in Items:
print(" x(", i, "): ", p.getSolution(x[i]))   