每隔n个位置将列表中的项目插入到另一个列表中 [英] Insert items from list to another list every n positions

问题描述

我有以下列表.

vector = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
inserted_elements = [2, 2, 2, 2, 2]

我想通过每两个元素插入以下内容.

I want to get the following by inserting every two elements.

output = [1, 2, 2, 3, 4, 2, 5, 6, 2, 7, 8, 2, 9, 10, 2]

不仅Python列表而且使用numpy数组的答案都很好.

Not only the Python list but also the answer using numpy array is fine.

推荐答案

这是一个 <基于 code>itertools 的方法，该方法也适用于从一个列表插入到另一个列表的任意数量的元素.为此，我定义了一个生成器函数，它将每个 i 项中的 l2 中的元素和元素插入 l1 中:

Here's an itertools based approach, which also works for an arbitrary number of elements to be inserted from one list to the other. For this I've defined a generator function, which will insert and element from l2 into l1 every i items:

def insert_every_n(l1, l2, k):
    i1, i2 = iter(l1), iter(l2)
    while True:
        try:
            yield from islice(i1, k)
            yield next(i2)
        except StopIteration:
            return

---

这可以通过使用 从 产生的收益所产生的项与切片的可迭代项中的项一样多，因此可迭代项用尽了(用于g中v的快捷方式:yield v ).

最后，我们可以用 try / expect 包裹 yield 语句，以捕获 StopIteration 警告.

Finally we can wrap the yield statements with a try/expect to catch the StopIteration warning.

让我们尝试以下示例:

vector = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
inserted_elements = [2, 2, 2, 2, 2]

list(insert_every_n(vector, inserted_elements, k=2))
# [1, 2, 2, 3, 4, 2, 5, 6, 2, 7, 8, 2, 9, 10, 2]

如果我们想每3个项目添加一个 l2 个项目:

And if we wanted to add an item of l2 every 3 items:

vector = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
inserted_elements = [2, 2, 2, 2]

list(insert_every_n(vector, inserted_elements, k=3))
# [1, 2, 3, 2, 4, 5, 6, 2, 7, 8, 9, 2, 10, 2]

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