Construct penalty function:
- p1 = (max(0, 4642 - X[0] - X[1] - X[2] - X[3] - X[4] - X[5] - X[6] - X[7] - X[8] - X[9])) ** 2
- p2 = (max(0, 23833 - X[10] - X[11] - X[12] - X[13] - X[14] - X[15] - X[16] - X[17])) ** 2
- p3 = (max(0, 8155 - X[18] - X[19] - X[20] - X[21] - X[22] - X[23] - X[24] - X[25] - X[26] - X[27] - X[28] - X[29])) ** 2
- If there are equality constraints, such as x1+2*x2=m, it can also be converted into a penalty function:
- p4=(x1+2*x2-m)**2
- P(x)=p1+p2+p3+......
- Construct augmented objective function
- L(x,m(k))=min(fx)+m(k)*P(x)
- m(k): Penalty factor, which gradually increases with the number of iterations k of the outer loop, but remains unchanged in the inner loop
# -*- coding: utf-8 -*-
import math # 导入模块
import random # 导入模块
import pandas as pd # 导入模块 YouCans, XUPT
import numpy as np # 导入模块 numpy,并简写成 np
import matplotlib.pyplot as plt
from datetime import datetime
# 子程序:定义优化问题的目标函数
def cal_Energy(X, nVar, mk): # m(k):惩罚因子,随迭代次数 k 逐渐增大
p1 = (max(0, 4642 - X[0] - X[1] - X[2] - X[3] - X[4] - X[5] - X[6] - X[7] - X[8] - X[9])) ** 2
p2 = (max(0, 23833 - X[10] - X[11] - X[12] - X[13] - X[14] - X[15] - X[16] - X[17])) ** 2
p3 = (max(0, 8155 - X[18] - X[19] - X[20] - X[21] - X[22] - X[23] - X[24] - X[25] - X[26] - X[27] - X[28] - X[
29])) ** 2
fx = (X[0] + X[1] + X[2] + X[3] + X[4] + X[5] + X[6] + X[7] + X[8] + X[9]) * 1.2 + (
X[10] + X[11] + X[12] + X[13] + X[14] + X[15] + X[16] + X[17]) * 1.1 + \
(X[18] + X[19] + X[20] + X[21] + X[22] + X[23] + X[24] + X[25] + X[26] + X[27] + X[28] + X[29])
return fx + mk * (p1 + p2 + p3)
# 子程序:模拟退火算法的参数设置
def ParameterSetting():
cName = "funcOpt" # 定义问题名称 YouCans, XUPT
nVar = 30 # 给定自变量数量,y=f(x1,..xn)
# xMin = [0, 0] # 给定搜索空间的下限,x1_min,..xn_min
# xMax = [8, 7.5] # 给定搜索空间的上限,x1_max,..xn_max
xMin = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
xMax = [3147, 30977, 1724, 966, 971, 7661, 9385, 2521, 699, 36972, 7885, 10207, 1181, 9768, 8181, 1014, 21293,
2081, 2816, 21267, 1788, 736, 922, 595, 15114, 23695, 5398, 342, 2005, 381]
tInitial = 100.0 # 设定初始退火温度(initial temperature)
tFinal = 1 # 设定终止退火温度(stop temperature)
alfa = 0.98 # 设定降温参数,T(k)=alfa*T(k-1)
meanMarkov = 100 # Markov链长度,也即内循环运行次数
scale = 0.5 # 定义搜索步长,可以设为固定值或逐渐缩小
return cName, nVar, xMin, xMax, tInitial, tFinal, alfa, meanMarkov, scale
# 模拟退火算法
def OptimizationSSA(nVar, xMin, xMax, tInitial, tFinal, alfa, meanMarkov, scale):
# ====== 初始化随机数发生器 ======
randseed = random.randint(1, 100)
random.seed(randseed) # 随机数发生器设置种子,也可以设为指定整数
# ====== 随机产生优化问题的初始解 ======
xInitial = np.zeros((nVar)) # 初始化,创建数组
for v in range(nVar):
# random.uniform(min,max) 在 [min,max] 范围内随机生成一个实数
xInitial[v] = random.uniform(xMin[v], xMax[v])
# 调用子函数 cal_Energy 计算当前解的目标函数值
fxInitial = cal_Energy(xInitial, nVar, 1) # m(k):惩罚因子,初值为 1
# ====== 模拟退火算法初始化 ======
xNew = np.zeros((nVar)) # 初始化,创建数组
xNow = np.zeros((nVar)) # 初始化,创建数组
xBest = np.zeros((nVar)) # 初始化,创建数组
xNow[:] = xInitial[:] # 初始化当前解,将初始解置为当前解
xBest[:] = xInitial[:] # 初始化最优解,将当前解置为最优解
fxNow = fxInitial # 将初始解的目标函数置为当前值
fxBest = fxInitial # 将当前解的目标函数置为最优值
print('x_Initial:{:.6f},{:.6f},\tf(x_Initial):{:.6f}'.format(xInitial[0], xInitial[1], fxInitial))
recordIter = [] # 初始化,外循环次数
recordFxNow = [] # 初始化,当前解的目标函数值
recordFxBest = [] # 初始化,最佳解的目标函数值
recordPBad = [] # 初始化,劣质解的接受概率
kIter = 0 # 外循环迭代次数,温度状态数
totalMar = 0 # 总计 Markov 链长度
totalImprove = 0 # fxBest 改善次数
nMarkov = meanMarkov # 固定长度 Markov链
# ====== 开始模拟退火优化 ======
# 外循环,直到当前温度达到终止温度时结束
tNow = tInitial # 初始化当前温度(current temperature)
while tNow >= tFinal: # 外循环,直到当前温度达到终止温度时结束
# 在当前温度下,进行充分次数(nMarkov)的状态转移以达到热平衡
kBetter = 0 # 获得优质解的次数
kBadAccept = 0 # 接受劣质解的次数
kBadRefuse = 0 # 拒绝劣质解的次数
# ---内循环,循环次数为Markov链长度
for k in range(nMarkov): # 内循环,循环次数为Markov链长度
totalMar += 1 # 总 Markov链长度计数器
# ---产生新解
# 产生新解:通过在当前解附近随机扰动而产生新解,新解必须在 [min,max] 范围内
# 方案 1:只对 n元变量中的一个进行扰动,其它 n-1个变量保持不变
xNew[:] = xNow[:]
v = random.randint(0, nVar - 1) # 产生 [0,nVar-1]之间的随机数
xNew[v] = xNow[v] + scale * (xMax[v] - xMin[v]) * random.normalvariate(0, 1)
# random.normalvariate(0, 1):产生服从均值为0、标准差为 1 的正态分布随机实数
xNew[v] = max(min(xNew[v], xMax[v]), xMin[v]) # 保证新解在 [min,max] 范围内
# ---计算目标函数和能量差
# 调用子函数 cal_Energy 计算新解的目标函数值
fxNew = cal_Energy(xNew, nVar, kIter)
deltaE = fxNew - fxNow
# ---按 Metropolis 准则接受新解
# 接受判别:按照 Metropolis 准则决定是否接受新解
if fxNew < fxNow: # 更优解:如果新解的目标函数好于当前解,则接受新解
accept = True
kBetter += 1
else: # 容忍解:如果新解的目标函数比当前解差,则以一定概率接受新解
pAccept = math.exp(-deltaE / tNow) # 计算容忍解的状态迁移概率
if pAccept > random.random():
accept = True # 接受劣质解
kBadAccept += 1
else:
accept = False # 拒绝劣质解
kBadRefuse += 1
# 保存新解
if accept == True: # 如果接受新解,则将新解保存为当前解
xNow[:] = xNew[:]
fxNow = fxNew
if fxNew < fxBest: # 如果新解的目标函数好于最优解,则将新解保存为最优解
fxBest = fxNew
xBest[:] = xNew[:]
totalImprove += 1
scale = scale * 0.99 # 可变搜索步长,逐步减小搜索范围,提高搜索精度
# ---内循环结束后的数据整理
# 完成当前温度的搜索,保存数据和输出
pBadAccept = kBadAccept / (kBadAccept + kBadRefuse) # 劣质解的接受概率
recordIter.append(kIter) # 当前外循环次数
recordFxNow.append(round(fxNow, 4)) # 当前解的目标函数值
recordFxBest.append(round(fxBest, 4)) # 最佳解的目标函数值
recordPBad.append(round(pBadAccept, 4)) # 最佳解的目标函数值
if kIter % 10 == 0: # 模运算,商的余数
print('i:{},t(i):{:.2f}, badAccept:{:.6f}, f(x)_best:{:.6f}'. \
format(kIter, tNow, pBadAccept, fxBest))
# 缓慢降温至新的温度,降温曲线:T(k)=alfa*T(k-1)
tNow = tNow * alfa
kIter = kIter + 1
fxBest = cal_Energy(xBest, nVar, kIter) # 由于迭代后惩罚因子增大,需随之重构增广目标函数
# ====== 结束模拟退火过程 ======
print('improve:{:d}'.format(totalImprove))
return kIter, xBest, fxBest, fxNow, recordIter, recordFxNow, recordFxBest, recordPBad
# 结果校验与输出
def ResultOutput(cName, nVar, xBest, fxBest, kIter, recordFxNow, recordFxBest, recordPBad, recordIter):
# ====== 优化结果校验与输出 ======
fxCheck = cal_Energy(xBest, nVar, kIter)
if abs(fxBest - fxCheck) > 1e-3: # 检验目标函数
print("Error 2: Wrong total millage!")
return
else:
print("\nOptimization by simulated annealing algorithm:")
for i in range(nVar):
print('\tx[{}] = {:.6f}'.format(i, xBest[i]))
print('\n\tf(x):{:.6f}'.format(cal_Energy(xBest, nVar, 0)))
return
# 主程序= 关注 Youcans,分享原创系列 https://blog.csdn.net/youcans =
def main(): # YouCans, XUPT
# 参数设置,优化问题参数定义,模拟退火算法参数设置
[cName, nVar, xMin, xMax, tInitial, tFinal, alfa, meanMarkov, scale] = ParameterSetting()
# print([nVar, xMin, xMax, tInitial, tFinal, alfa, meanMarkov, scale])
# 模拟退火算法
[kIter, xBest, fxBest, fxNow, recordIter, recordFxNow, recordFxBest, recordPBad] \
= OptimizationSSA(nVar, xMin, xMax, tInitial, tFinal, alfa, meanMarkov, scale)
# print(kIter, fxNow, fxBest, pBadAccept)
# 结果校验与输出
ResultOutput(cName, nVar, xBest, fxBest, kIter, recordFxNow, recordFxBest, recordPBad, recordIter)
# = 关注 Youcans,分享原创系列 https://blog.csdn.net/youcans =
if __name__ == '__main__':
main()
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