Python实现模拟退火算法求解VRP问题

Python实现模拟退火算法求解VRP问题

python代码实现

import pandas as pd
import math
import random
import numpy as np
import copy
import xlsxwriter
import matplotlib.pyplot as plt
class Sol():
    def __init__(self):
        self.nodes_seq=None
        self.obj=None
        self.routes=None
class Node():
    def __init__(self):
        self.id=0
        self.name=''
        self.seq_no=0
        self.x_coord=0
        self.y_coord=0
        self.demand=0
class Model():
    def __init__(self):
        self.best_sol=None
        self.node_list=[]
        self.node_seq_no_list=[]
        self.depot=None
        self.number_of_nodes=0
        self.opt_type=0
        self.vehicle_cap=0

def readXlsxFile(filepath,model):
    # It is recommended that the vehicle depot data be placed in the first line of xlsx file
    node_seq_no = -1#the depot node seq_no is -1,and demand node seq_no is 0,1,2,...
    df = pd.read_excel(filepath)
    for i in range(df.shape[0]):
        node=Node()
        node.id=node_seq_no
        node.seq_no=node_seq_no
        node.x_coord= df['x_coord'][i]
        node.y_coord= df['y_coord'][i]
        node.demand=df['demand'][i]
        if df['demand'][i] == 0:
            model.depot=node
        else:
            model.node_list.append(node)
            model.node_seq_no_list.append(node_seq_no)
        try:
            node.name=df['name'][i]
        except:
            pass
        try:
            node.id=df['id'][i]
        except