动态嵌套循环 Python

Question

这是我需要的数组：

N = 6
A = [[x,y,z] for x in range(N+1) for y in range(N+1) for z in range(N+1) if x+y+z== N]

有没有其他方法可以通过仅指定变量 N 和 3 而不是 x,y,z 来做到这一点？
我尝试了 []*3 但无法获得所需的输出。

Answer 1

您正在寻找iterttols.product：

from itertools import product

N = 6
A = [(x,y,z) for x in range(N+1) for y in range(N+1) for z in range(N+1) if x+y+z== N]
B = [tup for tup in product(range(N+1), repeat=3) if sum(tup) == N]
print(A, B, A == B, sep='\n')

给出：

[(0, 0, 6), (0, 1, 5), (0, 2, 4), (0, 3, 3), (0, 4, 2), (0, 5, 1), (0, 6, 0), (1, 0, 5), (1, 1, 4), (1, 2, 3), (1, 3, 2), (1, 4, 1), (1, 5, 0), (2, 0, 4), (2, 1, 3), (2, 2, 2), (2, 3, 1), (2, 4, 0), (3, 0, 3), (3, 1, 2), (3, 2, 1), (3, 3, 0), (4, 0, 2), (4, 1, 1), (4, 2, 0), (5, 0, 1), (5, 1, 0), (6, 0, 0)]
[(0, 0, 6), (0, 1, 5), (0, 2, 4), (0, 3, 3), (0, 4, 2), (0, 5, 1), (0, 6, 0), (1, 0, 5), (1, 1, 4), (1, 2, 3), (1, 3, 2), (1, 4, 1), (1, 5, 0), (2, 0, 4), (2, 1, 3), (2, 2, 2), (2, 3, 1), (2, 4, 0), (3, 0, 3), (3, 1, 2), (3, 2, 1), (3, 3, 0), (4, 0, 2), (4, 1, 1), (4, 2, 0), (5, 0, 1), (5, 1, 0), (6, 0, 0)]
True

Answer 2

使用itertools.combinations_with_replacement:

from itertools import combinations_with_replacement
n = 6
k = 3

# If you want a list of tuples:
lst = [item for item in list(combinations_with_replacement(range(n), k)) if sum(item) == n]
print(lst)
# [(0, 1, 5), (0, 2, 4), (0, 3, 3), (1, 1, 4), (1, 2, 3), (2, 2, 2)]

# If you want a list of lists:
lst = [list(item) for item in list(combinations_with_replacement(range(n), k)) if sum(item) == n]
print(lst)
# [[0, 1, 5], [0, 2, 4], [0, 3, 3], [1, 1, 4], [1, 2, 3], [2, 2, 2]]

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