如何并行访问两个子列表？

Question

I apologize if there is a duplicate, but I searched and could not find any topics that address my current issue.

I want to know if there is some pythonic way to iterate through two (or more) sublists in parallel. I'm already well aware of the zip function, so I will use it in a short example to explain what I want to do. Let's say I have the following two lists:

list1 = [1,2,3]
list2 = [4,5,6]

I know that I can iterate through them simultaneously like this:

>>> newlist = [i+j for i,j in zip(list1, list2)]
>>> newlist
[5,7,9]

However, with the way my data is being handled, I would like to do something slightly different. Instead of two independent lists, my data storage looks more like this:

biglist = [[1,2,3], [4,5,6]]

I know I could extract each sublist to be it's own variable, but I was moreso hoping I could do something more like this:

newbiglist = [i+j for i,j in zip(biglist)]

Where python would be able to recognize that there are two sublists in biglist . Does anyone know of any function that could do something like this?

Answer 1

Have you tried

newbiglist = [i+j for i,j in zip(*biglist)]

The "star" or "splat" operator * splits the variable into its components for use as parameters.

The result then of

print(newbiglist)

is what you want:

[5, 7, 9]

Note that this will give an error if biglist contains something other than two lists. There are several ways to handle a differing number of lists: the answer by @crook handles that nicely, and there are other ways.

Answer 2

for two or more you could try this

[sum(i) for i in  zip(*biglist)]

here i will be iterable, so you can use any function which accepts iterable or you can write your own.