nsga-ii算法中非支配排序的Python代码
时间: 2023-09-02 07:09:01 浏览: 52
以下是 NSGA-II 算法中的非支配排序的 Python 代码实现:
```python
def non_dominated_sorting(population):
# 初始化每个个体的支配集合和支配数
for p in population:
p.domination_count = 0
p.dominated_solutions = set()
# 初始化每个个体的等级(rank)
rank = 1
front = set()
for p in population:
p.rank = -1
# 对每个个体进行支配关系的比较
for p in population:
for q in population:
if p == q:
continue
if p.objectives <= q.objectives and p.id != q.id:
p.dominated_solutions.add(q)
elif p.objectives >= q.objectives and p.id != q.id:
p.domination_count += 1
if p.domination_count == 0:
p.rank = rank
front.add(p)
# 进行等级(rank)的计算
while front:
next_front = set()
for p in front:
for q in p.dominated_solutions:
q.domination_count -= 1
if q.domination_count == 0:
q.rank = rank+1
next_front.add(q)
rank += 1
front = next_front
```
其中,population 是一个个体列表,每个个体都有自己的 objectives(目标函数值)和 id(个体编号)。该代码实现了 NSGA-II 算法中的非支配排序过程,并将每个个体的等级(rank)和支配集合(dominated_solutions)保存在了个体对象中。