使用zip_longest对不同的长度列表求和并从开始而不是结束填充不同的长度 [英] Using zip_longest to sum different length lists and fill different lengths from start rather than end

问题描述

我有两个列表[1,2,3,4]和[1,2,3]

我想总结一下这些内容，以便给我以下内容:[1,3,5,7].

I would like to sum these to give me the following: [1,3,5,7].

这是通过执行1+0=1，2+1=3，3+2=5和4+3=7来完成的.

This was done by doing 1+0=1, 2+1=3, 3+2=5 and 4+3=7.

我知道itertools.zip_longest可以做到这一点，但最终会用0填补长度上的不匹配，给了我[2,3,6,4]而不是我想要的值.

I understand that itertools.zip_longest would do this, but it would fill the mismatch in length with 0 at the end, giving me [2,3,6,4] and not the value I want.

我希望通过用零填充第一长度来解决长度不匹配的问题.

I would like the mismatch in length to be solved by filling the first length with zero.

推荐答案

内置的

The built-in reversed() function could be used to do it like this:

from itertools import zip_longest    

def sum_lists(*iterables):
    iterables = (reversed(it) for it in iterables)
    return list(reversed([a+b for a, b in zip_longest(*iterables, fillvalue=0)]))


if __name__ == '__main__':
    result = sum_lists([1, 2, 3, 4], [1, 2, 3])
    print(result)  # -> [1, 3, 5, 7]
    result = sum_lists([1, 2, 3], [1, 2, 3, 4])
    print(result)  # -> [1, 3, 5, 7]    # Order of args doesn't matter.

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