集合的所有子集附加Nonetype Error

时间：2013-10-14 06:12:34

标签： python python-2.7

我正在尝试查找集合的所有子集并将其打印到列表中。 但是，我目前遇到此错误。

错误：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "subset_of_set.py", line 15, in <module>
    print subsets(a)
  File "subset_of_set.py", line 9, in subsets
    return subsets(setys, count + 1, main_list.append(sublist))
  File "subset_of_set.py", line 9, in subsets
    return subsets(setys, count + 1, main_list.append(sublist))
AttributeError: 'NoneType' object has no attribute 'append'

但是当我在解释器上测试.append时，似乎很好。

>>> f = []
>>> f.append(3)
>>> f
[3]

我可能缺少或不知道。有人可以解释一下吗？谢谢！

我的代码：

def subsets(setys, count = 1,main_list = []):
    set_to_list = list(setys)
    length_of_set = len(setys)
    sublist = []
    if count == length_of_set:
        return set(main_list)
    for n in set_to_list[:count]:
        sublist.append(n)
    return subsets(setys, count + 1, main_list.append(sublist))


a = [3,5,3,2,5,7,34,2,54,6,7,1,1,1,0,None,3,99,9]
a = set(a)

print subsets(a)

2 个答案:

答案 0 :(得分：2)

return subsets(setys, count + 1, main_list.append(sublist))确实是您的错误所在。考虑将其更改为

main_list.append(sublist)
return subsets(setys, count + 1, main_list)

答案 1 :(得分：2)

这里有两件事是错的：

<强>第一 

return set(main_list)

使用：return main_list代替。

For，Set需要一个hashable类型，哪个列表不是，因为list是可变的。你也可以在这里使用一个不可变的元组。

<强>另一个

您不能追加并同时将main_list的引用传递给递归。如下所示：

main_list.append(sublist)
    return subsets(setys, count + 1, main_list)

适合你。

输出：

[]
[[0]]
[[0], [0, 1], [0, 1]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99]]
[[0], [0, 1], [0, 1], [0, 1, 34], [0, 1, 34], [0, 1, 34], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99], [0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99]]

修改

将此添加到您的return语句中：

final_set = set()
        for item in tuple(main_list):
            final_set.add(tuple(item))
        return list(final_set)

最终输出： 

[(0, 1), (0,), (0, 1, 34, 3, 5, 6, 7, 9, 2, None, 99), (0, 1, 34), (0, 1, 34, 3, 5, 6, 7, 9, 2), (0, 1, 34, 3, 5), (0, 1, 34, 3, 5, 6, 7), (0, 1, 34, 3, 5, 6, 7, 9), (0, 1, 34, 3, 5, 6), (0, 1, 34, 3, 5, 6, 7, 9, 2, None), (0, 1, 34, 3)]
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