PuLP：目标函数：连接多个 lpSum

Question

我试图将几个lpSum表达式连接到一个长表达式，这将是我的目标函数。然而，我以优雅的方式合并这些表达式的尝试导致了不希望的结果。我想要这样的东西：a = pulp.lpSum(...)b = pulp.lpSum(...)c = pulp.lpSum(...)prob += a + b - c对我的代码更具体：    alloc_prob = pulp.LpProblem("Supplier Allocation Problem", pulp.LpMinimize)    TPC_func = pulp.lpSum(X[s][p]*procCosts[s][p] for s in supplier for p in     project), "Total Procurement Costs"    TTC_func = pulp.lpSum(X[s][p]*transCosts[s][p] for s in supplier for p in     project), "Total Transportation Costs (incl. taxes/duties)"    TD_func = pulp.lpSum(X_SEP[c][1]*discountFactor['Bonus / ton [€/t]'][c] for     c in company), "Total Discounts"`    # Objective function: TPC + TTC - TD -> min    alloc_prob += TPC_func  + TTC_func - TD_func我已经尝试过不同的嵌套方法，例如：    prob += [pulp.lpSum(X[s][p]*procCosts[s][p] + X[s][p]*transCosts[s][p] for s     in supplier for p in project) - pulp.lpSum(X_SEP[c][1]*discountFactor['Bonus     / ton [€/t]'][c] for c in company)]输出做它应该做的。然而，这既不是一个很好的代码，也不能分配给目标函数。有没有聪明的实施方式？

Answer 1

没有看到错误，我可以 100% 确定，但我认为您在 lpsum 中包含的名称导致了问题，请尝试以下操作

alloc_prob = pulp.LpProblem("Supplier Allocation Problem", pulp.LpMinimize)

TPC_func = pulp.lpSum(X[s][p]*procCosts[s][p] for s in supplier for p in 

project)

TTC_func = pulp.lpSum(X[s][p]*transCosts[s][p] for s in supplier for p in 

project)

TD_func = pulp.lpSum(X_SEP[c][1]*discountFactor['Bonus / ton [€/t]'][c] for 

c in company)

# Objective function: TPC + TTC - TD -> min

alloc_prob += TPC_func  + TTC_func - TD_func