在python中的列表中每個項目的左側和右側迭代n個元素的切片

Question

假設我有以下列表：

>>> my_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

我想編寫一個函數，該函數將在此列表的每個項目的左側和右側迭代n元素的切片：

def sliding_window_n_elements_left_and_right(lst, n):
    ...

該函數應該像這樣工作：

>>> list(sliding_window_n_elements_left_and_right(my_list, 0))
[[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]]

>>> list(sliding_window_n_elements_left_and_right(my_list, 1))
[[0, 1], [0, 1, 2], [1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6], [5, 6, 7], [6, 7, 8], [7, 8, 9], [8, 9, 10], [9, 10]]

>>> list(sliding_window_n_elements_left_and_right(my_list, 2))
[[0, 1, 2], [0, 1, 2, 3], [0, 1, 2, 3, 4], [1, 2, 3, 4, 5], [2, 3, 4, 5, 6], [3, 4, 5, 6, 7], [4, 5, 6, 7, 8], [5, 6, 7, 8, 9], [6, 7, 8, 9, 10], [7, 8, 9, 10], [8, 9, 10]]

感謝您的時間和技能！

Answer 1

您可以在每個索引處對列表進行切片i在左側和右側填充n以創建最大大小2n+1的固定窗口：

def sliding_window_n_elements_left_and_right(lst, n):
    # start = max(0, i-n) prevents slice from starting at negative value
    return [lst[max(0, i-n):i+n+1] for i in range(len(lst))]

---

print(sliding_window_n_elements_left_and_right(my_list, 0))
# [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]]

print(sliding_window_n_elements_left_and_right(my_list, 1))
# [[0, 1], [0, 1, 2], [1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6], [5, 6, 7], [6, 7, 8], [7, 8, 9], [8, 9, 10], [9, 10]]

print(sliding_window_n_elements_left_and_right(my_list, 2))
# [[0, 1, 2], [0, 1, 2, 3], [0, 1, 2, 3, 4], [1, 2, 3, 4, 5], [2, 3, 4, 5, 6], [3, 4, 5, 6, 7], [4, 5, 6, 7, 8], [5, 6, 7, 8, 9], [6, 7, 8, 9, 10], [7, 8, 9, 10], [8, 9, 10]]