在Python中添加以列表推导形式设置的元素

Question

我有一套套装.我想为每个集合添加一个元素,我想用list comprehension来做这个.这是我尝试过的:

In [1]: sets1 = [set()]

In [2]: sets2 = [{1,2}, {1,2,3}]

In [3]: [e.add(0) for e in sets1]
Out[3]: [None]

In [4]: [e.add(0) for e in sets2]
Out[4]: [None, None]

我想要的输出是:

[{0}]
[{1,2,0}, {1,2,3,0}]

为什么上面的代码返回None而不是添加到列表中的元素,以及我如何使这个工作？

Answer 1

我会建议:

[e | {0} for e in sets1]

要么:

[e.union({0}) for e in sets1]