检索线性表达式值

Retrieving the linear expression value

我想知道如何检索线性表达式值以显示在我的结果中。在我的问题中,我有以下表达式:

total_cost = solver.Sum(supplier_cost[j] for j in range(num_suppliers))

我正试图以这种方式显示表达式的值:

print('Total cost = ', total_cost)

但是,print('Total cost = ', total_cost) 中显示的是:(我没有输入整个值,因为文本太长了)

Total cost =  ((((0.0 * <ortools.linear_solver.linear_solver_natural_api.VariableExpr object at 0x7fe188875898>) + (0.0 * <ortools.linear_solver.linear_solver_natural_api.VariableExpr object at 0x7fe188875048>) + (0.0 * <ortools.linear_solver.linear_solver_natural_api.VariableExpr object at 0x7fe188875ac8>) + (0.0 * <ortools.linear_solver.linear_solver_natural_...

正如@Stradivari 回答的那样,要检索表达式值,我们需要调用方法 solution_value()。

total_cost.solution_value()