问题描述
我有一个列表列表:
mat = [[1,2,3],[4,5,6],[1,2,3],[7,8,9],[4,5,6]]
我想转换成 set，即删除重复列表并从中创建一个新列表，其中仅包含 unique 列表.
and I want to convert into a set i.e. remove the repeating lists and creating a new list out of it which will only contain the unique lists.
在上述情况下，所需的答案将是
In above case the required answer will be
[[1,2,3],[4,5,6],[7,8,9]]
但是当我执行 set(mat) 时，它给了我错误
But when I do set(mat), it gives me error
TypeError: unhashable type: 'list'
TypeError: unhashable type: 'list'
你能解决我的问题吗?提前致谢！
Can you please solve my problem. Thanks in advance!
推荐答案
由于列表是可变的，它们不能被散列.最好的办法是将它们转换为元组并形成一个集合，像这样
Since the lists are mutable, they cannot be hashed. The best bet is to convert them to a tuple and form a set, like this
>>> mat = [[1,2,3],[4,5,6],[1,2,3],[7,8,9],[4,5,6]]
>>> set(tuple(row) for row in mat)
set([(4, 5, 6), (7, 8, 9), (1, 2, 3)])
我们遍历 mat，一次一个列表，将其转换为一个元组(它是不可变的，所以 sets 很酷)和生成器被发送到 set 函数.
We iterate through the mat, one list at a time, convert that to a tuple (which is immutable, so sets are cool with them) and the generator is sent to the set function.
如果您希望将结果作为列表列表，您可以通过将 set 函数调用的结果转换为列表来扩展相同的列表，如下所示
If you want the result as list of lists, you can extend the same, by converting the result of set function call, to lists, like this
>>> [list(item) for item in set(tuple(row) for row in mat)]
[[4, 5, 6], [7, 8, 9], [1, 2, 3]]
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