itertools

I have a list of arrays and I would like to get the cartesian product of the elements in the arrays. I will use an example to make this more concrete... itertools.product seems to do the trick but I am stuck in a little detail. arrays = [(-1,+1), (-2,+2), (-3,+3)]; If I do cp = list(itertools.product(arrays)); I get cp = cp0 = [((-1, 1),), ((-2, 2),), ((-3, 3),)] But what I want to get is cp1 = [(-1,-2,-3), (-1,-2,+3), (-1,+2,-3), (-1,+2,+3), ..., (+1,+2,-3), (+1,+2,+3)]. I have tried a few different things: cp = list(itertools.product(itertools.islice(arrays, len(arrays)))); cp = list

I'm trying to figure out the best way to merge two lists into all possible combinations. So, if I start with two lists like this: list1 = [1, 2] list2 = [3, 4] The resulting list will look like this: [[[1,3], [2,4]], [[1,4], [2,3]]] That is, it basically produces a list of lists, with all the potential combinations between the two. I've been working through itertools, which I'm pretty sure holds the answer, but I can't come up with a way to make it act this way. The closest I came was: list1 = [1, 2, 3, 4] list2 = [5, 6, 7, 8] print list(itertools.product(list1, list2)) Which produced: [(1, 5)

Every use I can think of for Python's itertools.repeat() class, I can think of another equally (possibly more) acceptable solution to achieve the same effect. For example: >>> [i for i in itertools.repeat('example', 5)] ['example', 'example', 'example', 'example', 'example'] >>> ['example'] * 5 ['example', 'example', 'example', 'example', 'example'] >>> list(map(str.upper, itertools.repeat('example', 5))) ['EXAMPLE', 'EXAMPLE', 'EXAMPLE', 'EXAMPLE', 'EXAMPLE'] >>> ['example'.upper()] * 5 ['EXAMPLE', 'EXAMPLE', 'EXAMPLE', 'EXAMPLE', 'EXAMPLE'] Is there any case in which it would be the most

I have this data: self.data = [(1, 1, 5.0), (1, 2, 3.0), (1, 3, 4.0), (2, 1, 4.0), (2, 2, 2.0)] When I run this code: for mid, group in itertools.groupby(self.data, key=operator.itemgetter(0)): for list(group) I get: [(1, 1, 5.0), (1, 2, 3.0), (1, 3, 4.0)] which is what I want. But if I use 1 instead of 0 for mid, group in itertools.groupby(self.data, key=operator.itemgetter(1)): to group by the second number in the tuples, I only get: [(1, 1, 5.0)] even though there are other tuples that have "1" in that 1 (2nd) position. itertools.groupby collects together contiguous items with the same key.

I have a list of list as in the code I attached. I want to link each sub list if there are any common values. I then want to replace the list of list with a condensed list of list. Examples: if I have a list [[1,2,3],[3,4]] I want [1,2,3,4] . If I have [[4,3],[1,2,3]] I want [4,3,1,2] . If I have [[1,2,3],[a,b],[3,4],[b,c]] I want [[1,2,3,4],[a,b,c]] or [[a,b,c],[1,2,3,4]] I don't care which one. I am almost there... My problem is when I have a case like [[1,2,3],[10,5],[3,8,5]] I want [1,2,3,10,5,8] but with my current code I get [1,2,3,8,10,5] Here is my code: import itertools a = [1,2,3] b