python将3个列表合并到1个列表中(python merge 3 lists into 1 list)

 简短而有效的解决方案： 
 
def splitList (lst, n):
    it = iter(lst)
    new = [[next(it) for _ in range(n)] for _ in range(len(lst) // n)]

    for i, x in enumerate(it):
        new[i].append(x)

    return new
 
>>> lst = ['milk', 'eggs', 'beef', 'oranges', 'dog food', 'chips', 'soda', 'bread']
>>> splitList(lst, 3)
[['milk', 'eggs', 'beef', 'soda'], ['oranges', 'dog food', 'chips', 'bread']]
>>> splitList([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 3)
[[1, 2, 3, 10], [4, 5, 6], [7, 8, 9]]
 
 首先创建一个我们用于一切的迭代器; 所以总的来说，我们只在列表中循环一次。 将创建的子列表的数量是len(lst) // n （整数除法舍入），并且对于每个子列表，我们从迭代器中获取n值。 
 
 之后，剩余的项目仍然会留在迭代器中，所以我们可以简单地迭代其余的项目并直接将它们附加到子列表中。 

A short but efficient solution:
 
def splitList (lst, n):
    it = iter(lst)
    new = [[next(it) for _ in range(n)] for _ in range(len(lst) // n)]

    for i, x in enumerate(it):
        new[i].append(x)

    return new
 
>>> lst = ['milk', 'eggs', 'beef', 'oranges', 'dog food', 'chips', 'soda', 'bread']
>>> splitList(lst, 3)
[['milk', 'eggs', 'beef', 'soda'], ['oranges', 'dog food', 'chips', 'bread']]
>>> splitList([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 3)
[[1, 2, 3, 10], [4, 5, 6], [7, 8, 9]]
 
This first creates a single iterator which we use for everything; so in total we only loop once over the list. The number of sublists that will be created is len(lst) // n (integer division rounds down), and for each sublist we take n values from the iterator.
 
After that, the remaining items will be still left in the iterator, so we can simply iterate over the rest of them and append them to the sublists directly.