Python排列順序

Question

listA = ["A","B","C","D"]

由此，我只需要以下輸出：

["A","B","C"]
["B","C","D"]
["C","D","A"]
["D","A","B"]

我在這里查看了有關置換的各種問題，但是到目前為止，我還無法實現。 任何幫助將不勝感激。

Answer 1

另一種方式-蠻力，

def permutation(L):
    for i in range(len(L)):
        x = L[i:i+3]
        length = len(x)
        if length != 3:
            x = x + L[:3-length]
        print(x)


L = ["A","B","C","D"]
permutation(L)

Answer 2

您可以使用itertools.cycle和itertools.islice 。

要獲得顯示的訂單（如@tobias_k建議）：

>>> from itertools import cycle, islice
>>> listA = ["A","B","C","D"]
>>> [list(islice(cycle(listA), i, i+3)) for i in range(len(listA))]
[['A', 'B', 'C'], ['B', 'C', 'D'], ['C', 'D', 'A'], ['D', 'A', 'B']]

要獲取其他順序排序：

>>> it = cycle(listA)
>>> [list(islice(it,3)) for _ in range(len(listA))]
[['A', 'B', 'C'], ['D', 'A', 'B'], ['C', 'D', 'A'], ['B', 'C', 'D']]

Answer 3

感謝您的所有答復。 我收到了一個想在這里分享的朋友的另一個答案。 就像這樣

listA = ["A","B","C","D"]
listB = listA + [listA[0]] + [listA[1]]

catch = []
for i in range(len(listA)):
    A = listB[i]
    B = listB[i+1]
    C = listB[i+2]
    catch.append([A,B,C])
print catch