如何将列表列表的后半部分作为列表列表？

Question

So I know that to get a single column, I'd have to write

a = list(zip(*f)[0])

and the resulting a will be a list containing the first element in the lists in f.

How do I do this to get more than one element per list? I tried

a = list(zip(*f)[1:19])

But it just returned a list of lists where the inner list is the composed of the ith element in every list.

Answer 1

The easy way is not to use zip() . Instead, use a list comprehension :

a = [sub[1:19] for sub in f]

If it is actually the second half that you are looking for:

a = [sub[len(sub) // 2:] for sub in f]

That will include the 3 in [1, 2, 3, 4, 5] . If you don't want to include it:

a = [sub[(len(sub) + 1) // 2:] for sub in f]

Answer 2

You should definitely prefer @zondo's solution for both performance and readability. However, a zip based solution is possible and would look as follows (in Python 2):

zip(*zip(*f)[1:19])

You should not consider this cycle of unpacking, zipping, slicing, unpacking and re-zipping in any serious code though ;)

In Python 3, you would have to cast both zip results to list , making this even less sexy.