奇怪的蟒蛇"nested"循环

Question

我在别人的项目中遇到过以下循环，我以前从未见过这样的语法。这有点像嵌套 for 循环的突变，但不完全是。无论如何，我应该如何解释这行代码？或者我该如何展开这个循环？

for a in [np.transpose(np.array([list(B['v'][x]) + [0,1] for x in (face[0], face[1], face[2])]))  for face in B['shape']]:
    facets.extend([np.do(r) * scale for x in inflate(a)])

Answer 1

np.array表达式的内容为：

[list(B['v'][x]) + [0,1] for x in (face[0], face[1], face[2])]

将上述称为*，正在迭代的外部列表的内容是：

[np.transpose(np.array(*)) for face in B['shape']]

将每个列表推导转换为 for 循环：

for face in B['shape']:
    y = [] # temporary variable
    for x in (face[0], face[1], face[2]):
        y.append(list(B['v'][x]) + [0, 1])
    # outer loop variable
    a = np.transpose(np.array(y)) 
    z = [] # temporary variable
    for x in inflate(a):
        z.append(np.do(r) * scale)
    facets.extend(z)