python - 动态嵌套循环 - 递归

Question

我想生成一个数字按升序排列的数字列表。

for x in range(1,10):
    for y in range(x,10):
        for z in range(y,10):
            print(x,y,z)

我是否可以将其转换为递归，以便我可以改变嵌套深度？

笔记：

在我的应用程序中，除了打印之外，我还有其他内容，我想尽量减少打印语句的负担。

我知道它不适合itertools.product我的目的，因为我必须稍后删除不必要的组合。

由于同样的原因，生成所有n数字并删除不必要的数字也不起作用

谢谢

标签： pythonfor-loopnested

Answer 1

你需要itertools.combinations_with_replacement()

>>> import itertools
>>> list(itertools.combinations_with_replacement(range(1, 10), 2))
[(1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6), (1, 7), (1, 8), (1, 9), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6), (2, 7), (2, 8), (2, 9), (3, 3), (3, 4), (3, 5), (3, 6), (3, 7), (3, 8), (3, 9), (4, 4), (4, 5), (4, 6), (4, 7), (4, 8), (4, 9), (5, 5), (5, 6), (5, 7), (5, 8), (5, 9), (6, 6), (6, 7), (6, 8), (6, 9), (7, 7), (7, 8), (7, 9), (8, 8), (8, 9), (9, 9)]

>>> list(itertools.combinations_with_replacement(range(1, 10), 3))
[(1, 1, 1), (1, 1, 2), (1, 1, 3), (1, 1, 4), (1, 1, 5), (1, 1, 6), (1, 1, 7), (1, 1, 8), (1, 1, 9), (1, 2, 2), (1, 2, 3), (1, 2, 4), (1, 2, 5), (1, 2, 6), (1, 2, 7), (1, 2, 8), (1, 2, 9), (1, 3, 3), (1, 3, 4), (1, 3, 5), (1, 3, 6), (1, 3, 7), (1, 3, 8), (1, 3, 9), (1, 4, 4), (1, 4, 5), (1, 4, 6), (1, 4, 7), (1, 4, 8), (1, 4, 9), (1, 5, 5), (1, 5, 6), (1, 5, 7), (1, 5, 8), (1, 5, 9), (1, 6, 6), (1, 6, 7), (1, 6, 8), (1, 6, 9), (1, 7, 7), (1, 7, 8), (1, 7, 9), (1, 8, 8), (1, 8, 9), (1, 9, 9), (2, 2, 2), (2, 2, 3), (2, 2, 4), (2, 2, 5), (2, 2, 6), (2, 2, 7), (2, 2, 8), (2, 2, 9), (2, 3, 3), (2, 3, 4), (2, 3, 5), (2, 3, 6), (2, 3, 7), (2, 3, 8), (2, 3, 9), (2, 4, 4), (2, 4, 5), (2, 4, 6), (2, 4, 7), (2, 4, 8), (2, 4, 9), (2, 5, 5), (2, 5, 6), (2, 5, 7), (2, 5, 8), (2, 5, 9), (2, 6, 6), (2, 6, 7), (2, 6, 8), (2, 6, 9), (2, 7, 7), (2, 7, 8), (2, 7, 9), (2, 8, 8), (2, 8, 9), (2, 9, 9), (3, 3, 3), (3, 3, 4), (3, 3, 5), (3, 3, 6), (3, 3, 7), (3, 3, 8), (3, 3, 9), (3, 4, 4), (3, 4, 5), (3, 4, 6), (3, 4, 7), (3, 4, 8), (3, 4, 9), (3, 5, 5), (3, 5, 6), (3, 5, 7), (3, 5, 8), (3, 5, 9), (3, 6, 6), (3, 6, 7), (3, 6, 8), (3, 6, 9), (3, 7, 7), (3, 7, 8), (3, 7, 9), (3, 8, 8), (3, 8, 9), (3, 9, 9), (4, 4, 4), (4, 4, 5), (4, 4, 6), (4, 4, 7), (4, 4, 8), (4, 4, 9), (4, 5, 5), (4, 5, 6), (4, 5, 7), (4, 5, 8), (4, 5, 9), (4, 6, 6), (4, 6, 7), (4, 6, 8), (4, 6, 9), (4, 7, 7), (4, 7, 8), (4, 7, 9), (4, 8, 8), (4, 8, 9), (4, 9, 9), (5, 5, 5), (5, 5, 6), (5, 5, 7), (5, 5, 8), (5, 5, 9), (5, 6, 6), (5, 6, 7), (5, 6, 8), (5, 6, 9), (5, 7, 7), (5, 7, 8), (5, 7, 9), (5, 8, 8), (5, 8, 9), (5, 9, 9), (6, 6, 6), (6, 6, 7), (6, 6, 8), (6, 6, 9), (6, 7, 7), (6, 7, 8), (6, 7, 9), (6, 8, 8), (6, 8, 9), (6, 9, 9), (7, 7, 7), (7, 7, 8), (7, 7, 9), (7, 8, 8), (7, 8, 9), (7, 9, 9), (8, 8, 8), (8, 8, 9), (8, 9, 9), (9, 9, 9)]