Python 如何制作一组列表
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How to make a set of lists
提问by Phani
I have a list of lists like this:
我有一个像这样的列表：
i = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]]
I would like to get a list containing "unique" lists (based on their elements) like:
我想得到一个包含“独特”列表（基于它们的元素）的列表，例如：
o = [[1, 2, 3], [2, 4, 5]]
I cannot use set()as there are non-hashable elements in the list. Instead, I am doing this:
我无法使用，set()因为列表中有不可散列的元素。相反，我正在这样做：
o = []
for e in i:
if e not in o:
o.append(e)
Is there an easier way to do this?
有没有更简单的方法来做到这一点？
采纳答案by u1860929
You can create a set of tuples, a set of lists will not be possible because of non hashable elements as you mentioned.
您可以创建一组元组，由于您提到的不可散列元素，因此无法创建一组列表。
>>> l = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]]
>>> set(tuple(i) for i in l)
{(1, 2, 3), (2, 4, 5)}
回答by boh717
You can convert each element to a tuple and then insert it in a set.
您可以将每个元素转换为元组，然后将其插入到集合中。
Here's some code with your example:
这是您的示例的一些代码：
tmp = set()
a = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]]
for i in a:
tmp.add(tuple(i))
tmpwill be like this:
tmp将是这样的：
{(1, 2, 3), (2, 4, 5)}
回答by Padraic Cunningham
i = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]]
print([ele for ind, ele in enumerate(i) if ele not in i[:ind]])
[[1, 2, 3], [2, 4, 5]]
If you consider [2, 4, 5]to be equal to [2, 5, 4]then you will need to do further checks
如果您认为[2, 4, 5]等于[2, 5, 4]那么您将需要做进一步的检查
回答by sohrab haghayegh
Here's another way to do it:
这是另一种方法：
I = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]]
mySet = set()
for j in range(len(I)):
mySet = mySet | set([tuple(I[j])])
print(mySet)
