交错4个相同长度的python列表

Question

我想在python中交错4个相同长度的列表。

我搜索了这个站点，只看到如何在python中交错2：Interleaving two lists in Python

能给出4个列表的建议吗？

我有这样的列表

l1 = ["a","b","c","d"]
l2 = [1,2,3,4]
l3 = ["w","x","y","z"]
l4 = [5,6,7,8]

我想要这样的列表

l5 = ["a",1,"w",5,"b",2,"x",6,"c",3,"y",7,"d",4,"z",8]

Answer 1

来自itertools菜谱

itertool recipes建议了一种名为roundrobin的解决方案，该方案允许不同长度的列表。

from itertools import cycle, islice

def roundrobin(*iterables):
    "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
    # Recipe credited to George Sakkis
    num_active = len(iterables)
    nexts = cycle(iter(it).__next__ for it in iterables)
    while num_active:
        try:
            for next in nexts:
                yield next()
        except StopIteration:
            # Remove the iterator we just exhausted from the cycle.
            num_active -= 1
            nexts = cycle(islice(nexts, num_active))

print(*roundrobin(*lists)) # a 1 w 5 b 2 x 6 c 3 y 7 d 4 z 8

使用切片

或者，这里是一个完全依赖于切片的解决方案，但要求所有列表的长度相同。

l1 = ["a","b","c","d"]
l2 = [1,2,3,4]
l3 = ["w","x","y","z"]
l4 = [5,6,7,8]

lists = [l1, l2, l3, l4]

lst = [None for _ in range(sum(len(l) for l in lists))]

for i, l in enumerate(lists):
    lst[i:len(lists)*len(l):len(lists)] = l

print(lst) # ['a', 1, 'w', 5, 'b', 2, 'x', 6, 'c', 3, 'y', 7, 'd', 4, 'z', 8]

Answer 2

只是为了多样性，numpy.dstack和flatten可以做同样的事情。

>>> import numpy as np
>>> l1 = ["a","b","c","d"]
>>> l2 = [1,2,3,4]
>>> l3 = ["w","x","y","z"]
>>> l4 = [5,6,7,8]
>>> np.dstack((np.array(l1),np.array(l2),np.array(l3),np.array(l4))).flatten()                                                                                                       
array(['a', '1', 'w', '5', 'b', '2', 'x', '6', 'c', '3', 'y', '7', 'd',                                                                                                              
       '4', 'z', '8'],                                                                                                                                                               
      dtype='|S21') 

顺便说一句，你实际上不需要创建一个数组，简短的版本也可以

>>> np.dstack((l1,l2,l3,l4)).flatten()                                                                                                       
array(['a', '1', 'w', '5', 'b', '2', 'x', '6', 'c', '3', 'y', '7', 'd',                                                                                                              
       '4', 'z', '8'],                                                                                                                                                               
      dtype='|S21')   

Answer 3

使用zip和reduce

import functools, operator
>>> functools.reduce(operator.add, zip(l1,l2,l3,l4))
('a', 1, 'w', 5, 'b', 2, 'x', 6, 'c', 3, 'y', 7, 'd', 4, 'z', 8)