*a, b, c = line.split() 中的星号有什么作用? [英] What does the asterisk do in *a, b, c = line.split()?

问题描述

假设 line 是:"Chicago Sun 01:52".

*a, b, c = line.split() 有什么作用?特别是星号的意义是什么?

What does *a, b, c = line.split() do? In particular, what is the significance of the asterisk?

经过测试，似乎"Chicago"、"Sun"和"01:52"都存储在a、b 和 c.星号似乎导致 "Chicago" 作为列表的第一个元素存储在 a 中.所以，我们有 a = ["Chicago"]、b = "Sun" 和 c = "01:52".在这种情况下，有人可以指出有关星号运算符功能的材料吗?

Upon testing it, it seems like "Chicago", "Sun" and "01:52" are all stored in a, b and c. The asterisk seems to lead to "Chicago" being stored in a as the first element of a list. So, we have a = ["Chicago"], b = "Sun" and c = "01:52". Could anyone point to material on the functionality of the asterisk operator in this situation?

推荐答案

用空格分割文本会给你:

Splitting that text by whitespace will give you:

In [743]: line.split()
Out[743]: ['Chicago', 'Sun', '01:52']

现在，这是一个 3 元素 list.赋值将把输出的最后两个元素分别赋值给 b 和 c.* 或 splat 运算符将把该列表的其余部分传递给 a，因此 a 是元素列表.在这种情况下，a 是一个单元素列表.

Now, this is a 3 element list. The assignment will take the last two elements of the output and assign them to b and c respectively. The *, or the splat operator will then pass the remainder of that list to a, and so a is a list of elements. In this case, a is a single-element list.

In [744]: *a, b, c = line.split()

In [745]: a
Out[745]: ['Chicago']

In [746]: b
Out[746]: 'Sun'

In [747]: c
Out[747]: '01:52'

查看 PEP 3132 和 python 的 splat 运算符 * 和 ** 在哪里有效? 有关 splat 运算符的更多信息，它们如何工作以及它们适用的地方.

Look at PEP 3132 and Where are python's splat operators * and ** valid? for more information on the splat operators, how they work and where they're applicable.

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