Python实现狼群算法解决01背包问题的完整代码
时间: 2023-08-06 07:05:26 浏览: 146
好的,以下是Python实现狼群算法解决01背包问题的完整代码:
```python
import random
# 定义狼群算法类
class WolfPackAlgorithm:
def __init__(self, n, m, w, v, c, p=0.8, a=2):
self.n = n # 物品数量
self.m = m # 背包容量
self.w = w # 物品重量
self.v = v # 物品价值
self.c = c # 狼群数量
self.p = p # 变异概率
self.a = a # 狼群半径
# 初始化狼群
def init_wolf_pack(self):
wolf_pack = []
for i in range(self.c):
wolf = [random.randint(0, 1) for j in range(self.n)]
wolf_pack.append(wolf)
return wolf_pack
# 计算适应度
def calc_fitness(self, wolf):
weight = sum([wolf[i] * self.w[i] for i in range(self.n)])
if weight > self.m:
return -1
else:
value = sum([wolf[i] * self.v[i] for i in range(self.n)])
return value
# 选择狼群中最优秀的狼
def select_alpha(self, wolf_pack):
alpha = wolf_pack[0]
alpha_fitness = self.calc_fitness(alpha)
for wolf in wolf_pack:
fitness = self.calc_fitness(wolf)
if fitness > alpha_fitness:
alpha = wolf
alpha_fitness = fitness
return alpha
# 更新狼群
def update_wolf_pack(self, wolf_pack, alpha):
new_wolf_pack = []
for wolf in wolf_pack:
# 狼群半径内没有更优秀的狼,按照原狼的行为进行
if wolf == alpha:
new_wolf = wolf.copy()
for i in range(self.n):
if random.random() < 1 / (1 + pow(2.71828, -self.a)):
new_wolf[i] = 1 - new_wolf[i]
new_wolf_pack.append(new_wolf)
# 狼群半径内存在更优秀的狼,按照更优秀的狼的行为进行
else:
new_wolf = wolf.copy()
for i in range(self.n):
if alpha[i] != wolf[i] and random.random() < 1 / (1 + pow(2.71828, -self.a)):
new_wolf[i] = alpha[i]
new_wolf_pack.append(new_wolf)
return new_wolf_pack
# 狼群算法求解01背包问题
def solve_knapsack_problem(self):
wolf_pack = self.init_wolf_pack()
for i in range(100):
alpha = self.select_alpha(wolf_pack)
new_wolf_pack = self.update_wolf_pack(wolf_pack, alpha)
for j in range(self.c):
if random.random() < self.p:
for k in range(self.n):
if random.random() < 0.5:
new_wolf_pack[j][k] = 1 - new_wolf_pack[j][k]
wolf_pack = new_wolf_pack
alpha = self.select_alpha(wolf_pack)
weight = sum([alpha[i] * self.w[i] for i in range(self.n)])
value = sum([alpha[i] * self.v[i] for i in range(self.n)])
return alpha, weight, value
# 测试代码
if __name__ == '__main__':
n = 10
m = 50
w = [random.randint(1, 10) for i in range(n)]
v = [random.randint(10, 100) for i in range(n)]
c = 20
wolf_pack_algorithm = WolfPackAlgorithm(n, m, w, v, c)
alpha, weight, value = wolf_pack_algorithm.solve_knapsack_problem()
print('最优解:', alpha)
print('重量:', weight)
print('价值:', value)
```
在上述代码中,我们定义了一个`WolfPackAlgorithm`类,其中包括初始化狼群、计算适应度、选择最优秀的狼、更新狼群等方法。最后,我们进行了测试,使用狼群算法求解了一个10个物品,背包容量为50的01背包问题,并输出了最优解、重量和价值。
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