如何大声阅读Python列表推导？

如何大声阅读Python列表推导？

我通常在脑海中将其展开为一个生成循环，例如

[(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]

是生成器的列表理解

for x in [1,2,3]:    for y in [3,1,4]:        if x != y: yield (x, y)

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例子1

[x for b in a for x in b]

是对

for b in a:    for x in b:        yield x

结果示例

a = [[1,2,3],[4,5,6]]

：

[1, 2, 3, 4, 5, 6]

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范例＃2

[[row[i] for row in matrix] for i in range(4)]

（请注意，内部表达式是另一种理解！）：

for i in range(4):    yield [row[i] for row in matrix]

展开了

for i in range(4):    l = []    for row in matrix:        l.append(row[i])    yield l