itertools

问题 I\'m trying to create a powerset in Python 3. I found a reference to the itertools module, and I\'ve used the powerset code provided on that page. The problem: the code returns a reference to an itertools.chain object, whereas I want access to the elements in the powerset. My question: how to accomplish this? Many thanks in advance for your insights. 回答1: itertools functions return iterators, objects that produce results lazily, on demand. You could either loop over the object with a for loop

问题 itertools.permutations generates where its elements are treated as unique based on their position, not on their value. So basically I want to avoid duplicates like this: >>> list(itertools.permutations([1, 1, 1])) [(1, 1, 1), (1, 1, 1), (1, 1, 1), (1, 1, 1), (1, 1, 1), (1, 1, 1)] Filtering afterwards is not possible because the amount of permutations is too large in my case. Does anybody know of a suitable algorithm for this? Thank you very much! EDIT: What I basically want is the following: