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Knapsack problem Description Example of a knapsack problem formulated with the Xpress Python interface. Further explanation of this example:
'Xpress Python Reference Manual'
Source Files knapsack.py # # Example of a knapsack problem formulated with the Xpress Python interface # import xpress as xp S = range(5) # that's the set {0,1,2,3,4} value = [102, 512, 218, 332, 41] # or just read them from file weight = [21, 98, 44, 59, 9] x = [xp.var(vartype=xp.binary) for i in S] profit = xp.Sum(value[i] * x[i] for i in S) p = xp.problem("knapsack") p.addVariable(x) p.addConstraint(xp.Sum(weight[i] * x[i] for i in S) <= 130) p.setObjective(profit, sense=xp.maximize) # A more compact (and equivalent) problem construction: # # p = xp.problem(x, xp.Sum(weight[i] * x[i] for i in S) <= 130, profit, sense=xp.maximize, name="knapsack") p.solve() | |||||||||

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