Question

我目前正在AI部门从事学校作业，在那里我必须制定遗传算法。它旨在使用称为板的列表来解决8 Queens问题，其中每个索引是一列，而该索引中的值是行。该算法本身运行良好，但是每次我尝试运行该算法时，while循环达到种群大小-2（在本例中为18）后就会崩溃。我得到的错误是关于行：

child = reproduce(population[l], population[l + 1], nqueens)

，错误是：

回溯（最近通话最近）：在第370行的文件“ nqueens1.py”中 main（）

文件“ nqueens1.py”，主行，第363行 Genetic_algorithm（board）

genetic_algorithm中的文件“ nqueens1.py”，第291行孩子=繁殖（人口[l]，人口[l + 1]，nqueens）

IndexError：列表索引超出范围

我试图了解问题出在哪里，但是我不明白为什么它会超出范围。这是我到目前为止的代码：

功能复制

def reproduce(boardX, boardY, nqueens):
boardChild = [-1] * nqueens 
n = random.randint(0, (nqueens - 1)) #percentage of how much of one parent is reproduced and how much of the other parent
d = 0
for d in range(n): # the first n part of parent x
    boardChild[d] = boardX[d]

s = d + 1
for s in range(nqueens) : # the last n-(len(board)-1) part of parent y
    boardChild[s] = boardY[s]

return boardChild

功能突变

def mutate(child):
print('mutate')

boardMutated = [-1] * len(child)
newColumn = random.randint(0, len(child)-1)
newRow = random.randint(0, len(child)-1)
boardMutated[newColumn] = newRow

return boardMutated

遗传算法

def genetic_algorithm(board):
optimum = (len(board) - 1) * len(board) / 2
print('optimum:' + str(optimum))
nqueens = len(board)
populationSize = 20

population = []

for i in range(populationSize -1): #initializes first pooulation
    population.append([])
    for _ in range(nqueens):
        population[i].append(random.randint(0, nqueens-1))
    population[i].append(evaluate_state(population[i]))

    if evaluate_state(population[i]) == optimum:
        print("solved puzzle! 0")
        print_board(population[i])
        return 

t = 0
while t != 1000:
    population.sort(key=lambda x: x[nqueens -1 ]) #sorts the population from highest population size
    for i in range(populationSize -1):
        del population[i][-1]
    newPopulation = [ [] for _ in range(populationSize -1) ]
    newPopulation[0] = reproduce(population[1], population[0], nqueens) #
    chance = random.randint(0, 100)
    if chance < 5: # small chance that the child gets mutated
            newPopulation[0] = mutate(newPopulation[0])
            if evaluate_state(newPopulation[0]) == optimum:
                print('if evaluate_state(child) == optimum:')
                print("Solved puzzle! 1")
                print_board(newPopulation[0])
                return

    if evaluate_state(newPopulation[0]) == optimum:
        print("Solved puzzle! 2")
        print('if evaluate_state(newPopulation[1]) == optimum:')
        print_board(newPopulation[1])
        return

    l = 0

    while l != (populationSize -1):
        print(str(l))
        child = reproduce(population[l], population[l + 1], nqueens) # reproduces the new generation
        print_board(child)
        if evaluate_state(child) == optimum:
            print('if evaluate_state(child) == optimum:')
            print("Solved puzzle! 3")
            print_board(child)
            return

        chance = random.randint(0, 100)
        if chance < 5: # small chance that the child gets mutated
            child = mutate(child)
            if evaluate_state(child) == optimum:
                print('if evaluate_state(child) == optimum:')
                print("Solved puzzle! 4")
                print_board(child)
                return

        newPopulation[l] = child
        l += 1
    t += 1

添加了所有打印语句，以查看哪些部分已执行，哪些未执行。一旦l在此处达到18，代码就会崩溃，这当然不应该崩溃。所有帮助将不胜感激！

Answer 1

我认为population只有19项，而不是20；所有种群均使用range(populationSize - 1)初始化，该变量只有19个数字（从0到18）。

您还可以通过打印出len(population)

进行检查

为什么此列表索引超出范围？

1 个答案: