如何使用 Python 将二维数组中的列分配给某个重复范围？

Question

我想将二维数组的列值分配给重复范围。
例如，范围将从 1 到 3:

[1, 0, 0]
[2, 0, 0]
[3, 0, 0]
[1, 0, 0]
[2, 0, 0]
[3, 0, 0]

我有代码：

width, height = 3, 6 
array2d = [[0 for x in range(width)] for y in range(height)]

repRange = list(range(1,4)) #it is [1, 2, 3]

j = 0
for i in range(height):    
    array2d[i][0] = repRange[j]

    if j >= len(repRange)-1:
        j = 0
    j += 1

for row in array2d:
    print(row)

输出：

[1, 0, 0]
[2, 0, 0]
[3, 0, 0]
[2, 0, 0]
[3, 0, 0]
[2, 0, 0]

失败了。开始很好，但在第二次重复时失败了。

逻辑有什么问题？如果有更简单的方法，希望大家分享。

Answer 1

看看标准库模块itertools。函数 cycle 做你想做的事：

from itertools import cycle
width, height = 3, 6 
array2d = [[0 for x in range(width)] for y in range(height)]
for l, i in zip(array2d, cycle([1,2,3])):
    l[0] = i

Answer 2

您的逻辑问题在于，当您到达 repRange 的末尾时，您将 j 设置为 1 而不是 0。发生这种情况是因为 j += 1 在if声明； if 语句中的测试也需要调整。这是您的代码的修复版本。

width, height = 3, 6 
array2d = [[0 for x in range(width)] for y in range(height)]

repRange = list(range(1, 4)) #it is [1, 2, 3]

j = 0
for i in range(height):
    array2d[i][0] = repRange[j]

    j += 1
    if j >= len(repRange):
        j = 0

for row in array2d:
    print(row)

输出

[1, 0, 0]
[2, 0, 0]
[3, 0, 0]
[1, 0, 0]
[2, 0, 0]
[3, 0, 0]

这是一个更紧凑的版本。

from itertools import cycle

width, height = 3, 6 
repRange = cycle(range(1, 4))
zeroes = [0] * (width - 1)
array2d = [[next(repRange)] + zeroes for y in range(height)]

for row in array2d:
    print(row)

还有一个：

from itertools import cycle

width, height = 3, 6 
zeroes = [0] * (width - 1)
array2d = [[v] + zeroes for _, v in zip(range(height), cycle(range(1, 4)))]

for row in array2d:
    print(row)

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