python - 如何在两个方向(向前，向后)获取每个元素的值的滑动窗口？

Question

我有一个这样的值列表，

lst = [1, 2, 3, 4, 5, 6, 7, 8]

期望输出 :

window size = 3
    1  # first element in the list
    forward = [2, 3, 4]
    backward = []

    2  # second element in the list
    forward = [3, 4, 5]
    backward = [1]

    3  # third element in the list
    forward = [4, 5, 6]
    backward = [1, 2]

    4  # fourth element in the list
    forward = [5, 6, 7]
    backward = [1, 2, 3]

    5  # fifth element in the list
    forward = [6, 7, 8]
    backward = [2, 3, 4]

    6  # sixth element in the list
    forward = [7, 8]
    backward = [3, 4, 5]

    7  # seventh element in the list
    forward = [8]
    backward = [4, 5, 6]

    8  # eight element in the list
    forward = []
    backward = [5, 6, 7]

让我们假设窗口大小为 4，现在我想要的输出:

对于列表中的 each_element，我想要前面的 4 个值和后面的 4 个值，忽略当前值。

我能够使用它来获取值的滑动窗口，但这也没有给我正确的所需输出。

import more_itertools
list(more_itertools.windowed([1, 2, 3, 4, 5, 6, 7, 8], n=3))

Answer 1

代码:

arr = [1, 2, 3, 4, 5, 6, 7, 8]
window = 3
for backward, current in enumerate(range(len(arr)), start = 0-window):
    if backward < 0:
        backward = 0
    print(arr[current+1:current+1+window], arr[backward:current])

输出:

[2, 3, 4], []
[3, 4, 5], [1]
[4, 5, 6], [1, 2]
[5, 6, 7], [1, 2, 3]
[6, 7, 8], [2, 3, 4]
[7, 8], [3, 4, 5]
[8], [4, 5, 6]
[], [5, 6, 7]

一个类轮:

print(dict([(e, (lst[i+1:i+4], lst[max(i-3,0):i])) for i,e in enumerate(last)]))

输出:

{1: ([2, 3, 4], []),
 2: ([3, 4, 5], [1]),
 3: ([4, 5, 6], [1, 2]),
 4: ([5, 6, 7], [1, 2, 3]),
 5: ([6, 7, 8], [2, 3, 4]),
 6: ([7, 8], [3, 4, 5]),
 7: ([8], [4, 5, 6]),
 8: ([], [5, 6, 7])}

信用:感谢@FeRD 和@Androbin 的建议，解决方案现在看起来更好