import pulp import matplotlib.pyplot as plt import sys # Create a problem variable: model = pulp.LpProblem("Optimal_Distribution", pulp.LpMinimize) # Define providers (Factories and Warehouses) factories = ['F1', 'F2'] warehouses = ['M1', 'M2', 'M3', 'M4'] providers = factories + warehouses # Combining both lists # Define customers customers = ['K1', 'K2', 'K3', 'K4', 'K5', 'K6'] cost = { 'F1': {'M1': 0.3, 'M2': 0.5, 'M3': 1.2, 'M4': 0.8, 'K1': 1.2, 'K2': 999, 'K3': 1.2, 'K4': 2.0, 'K5': 999, 'K6': 1.1}, 'F2': {'M1': 999, 'M2': 0.4, 'M3': 0.5, 'M4': 0.3, 'K1': 1.8, 'K2': 999, 'K3': 999, 'K4': 999, 'K5': 999, 'K6': 999}, 'M1': {'K1': 999, 'K2': 1.2, 'K3': 0.2, 'K4': 1.7, 'K5': 999, 'K6': 2.0}, 'M2': {'K1': 1.4, 'K2': 0.3, 'K3': 1.8, 'K4': 1.3, 'K5': 0.5, 'K6': 999}, 'M3': {'K1': 999, 'K2': 1.3, 'K3': 2.0, 'K4': 999, 'K5': 0.3, 'K6': 1.4}, 'M4': {'K1': 999, 'K2': 999, 'K3': 0.4, 'K4': 2.0, 'K5': 0.5, 'K6': 1.6} } # Decision variables x = pulp.LpVariable.dicts("x", [(i, j) for i in providers for j in customers], lowBound=0, cat='Integer') y = pulp.LpVariable.dicts("y", [(i, k) for i in factories for k in warehouses], lowBound=0, cat='Integer') # Objective function components cost_distribution = pulp.lpSum([cost[i][j] * x[(i, j)] for i in providers for j in customers]) cost_warehouse = pulp.lpSum([cost[i][k] * y[(i, k)] for i in factories for k in warehouses]) alpha = 0.5 beta = 0.5 # Binary variables for meeting preferences P = pulp.LpVariable.dicts("P", [(i, j) for i in providers for j in customers], cat='Binary') max_order = 60 satisfaction_scores = {'K1': 50 / max_order, 'K2': 10 / max_order, 'K3': 40 / max_order, 'K4': 35 / max_order, 'K5': 60 / max_order, 'K6': 20 / max_order} customer_preferences = {'K1': ['F2'], 'K2': ['M1'], 'K3': ['M2', 'M3'], 'K4': ['F1'], 'K5': [], 'K6': ['M3', 'M4']} # Satisfaction component satisfaction_component = pulp.lpSum([satisfaction_scores[j] * P[(i, j)] for i in providers for j in customers]) # Define objective model += alpha * (cost_distribution + cost_warehouse) - beta * satisfaction_component # Factory production capacity constraints factory_capacity = {'F1': 150, 'F2': 200} warehouse_capacity = {'M1': 70, 'M2': 50 , 'M3': 100, 'M4': 40 } customer_demand = {'K1': 50, 'K2': 10, 'K3': 40, 'K4': 35, 'K5': 60, 'K6': 20} for i in factories: model += pulp.lpSum([x[(i, j)] for j in customers] + [y[(i, k)] for k in warehouses]) <= factory_capacity[i] # Warehouse handling capacity constraints for k in warehouses: model += pulp.lpSum([x[(k, j)] for j in customers]) <= warehouse_capacity[k] # Customer demand fulfillment constraints for j in customers: model += pulp.lpSum([x[(i, j)] for i in providers]) == customer_demand[j] # Other constraints like preferences can be added similarly # Solve the problem # Output results for v in model.variables(): print(v.name, "=", v.varValue) # Assuming definitions of the model as previously discussed cost_results = [] satisfaction_results = [] # Varying alpha and beta for alpha in range(10): beta = 10 - alpha + sys.float_info.epsilon alpha /= 10.0 beta /= 10.0 # Update objective function model.objective = alpha * cost_distribution - beta * satisfaction_component # Solve the model model.solve() print(alpha) # Record the results # Record the results total_cost = pulp.value(cost_distribution) total_satisfaction = pulp.value(satisfaction_component) cost_results.append(total_cost) satisfaction_results.append(total_satisfaction) print(cost_results, satisfaction_results) # Plotting the results plt.plot(cost_results, satisfaction_results, marker='o') plt.xlabel('Total Cost') plt.ylabel('Customer Satisfaction') plt.title('Trade-off between Cost and Customer Satisfaction') plt.show()