不符合 PEP8 标准的大型嵌套循环

Question

我正在努力遵守 PEP8 准则，而我遇到的问题是 79 个字符的行限制。 如果我正在处理类似 10x10 数组的内容，我倾向于使用嵌套循环来访问数组的特定元素。 它看起来像这样：

size=10
for i in range(size):
    for k in range(size):
        for j in range(size):
            for l in range(size):
                for m in range(size):
                    for n in range(size):
                        for p in range(size):
                            for q in range(size):
                                for r in range(size):
                                    for s in range(size):
                                        matrix[i][k][j][l][m][n][p][q][r][s]=matrix[i][k][j][l][m][n][p][q][r][s]*matrix[i][k][j][l][m][n][p][q][r][s]

我应该如何更改它以适应字符行限制？

我递归地重写了代码并重命名了一些变量，现在它适合了！ 谢谢你。

size=10
def sq(element,power):
    if power==1:
        return element
    else:
        return element*sq(element,power-1)

for i in range(size):
    for j in range(size):
        for k in range(size):
            for l in range(size):
                for m in range(size):
                    for n in range(size):
                        for p in range(size):
                            for q in range(size):
                                for r in range(size):
                                    for s in range(size):
                                       x=l[i][j][k][l][m][n][p][q][r][s]
                                       l[i][j][k][l][m][n][p][q][r][s]=sq(x,2)

Answer 1

就像 cdlane 所做的那样，但也不手动处理索引。

from itertools import product, cycle
from pprint import pprint

def tuple_index(arr, index):
    """
    tuple_index(arr, [i, j, ..., k]) == arr[i][j]...[k]
    """
    result = arr
    for i in index:
        result = result[i]
    return result

def main():
    size = 4
    dimensions = 3

    # Build up sample matrix manually to test and demonstrate
    source = cycle(range(20))
    matrix = [[[next(source)
                for i in range(size)]
               for j in range(size)]
              for k in range(size)]
    print('Before:')
    pprint(matrix)

    for index in product(range(size), repeat=dimensions):
        inner_list = tuple_index(matrix, index[:-1])
        inner_list[index[-1]] *= inner_list[index[-1]]

    print('\nAfter:')
    pprint(matrix)

main()

输出：

Before:
[[[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11], [12, 13, 14, 15]],
 [[16, 17, 18, 19], [0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 10, 11]],
 [[12, 13, 14, 15], [16, 17, 18, 19], [0, 1, 2, 3], [4, 5, 6, 7]],
 [[8, 9, 10, 11], [12, 13, 14, 15], [16, 17, 18, 19], [0, 1, 2, 3]]]

After:
[[[0, 1, 4, 9], [16, 25, 36, 49], [64, 81, 100, 121], [144, 169, 196, 225]],
 [[256, 289, 324, 361], [0, 1, 4, 9], [16, 25, 36, 49], [64, 81, 100, 121]],
 [[144, 169, 196, 225], [256, 289, 324, 361], [0, 1, 4, 9], [16, 25, 36, 49]],
 [[64, 81, 100, 121],
  [144, 169, 196, 225],
  [256, 289, 324, 361],
  [0, 1, 4, 9]]]

Answer 2

尽管 numpy 可能会更优雅、更有效地处理这个问题，但您可以尝试以下操作：

from itertools import product

for indicies in product(range(size), repeat=size):
    (i, j, k, l, m, n, p, q, r, s) = indicies
    matrix[i][j][k][l][m][n][p][q][r][s] **= 2