集合差与集合减法 [英] Set difference versus set subtraction

问题描述

- 和 .difference() 在集合上有什么区别?显然语法不一样，一个是二元运算符，一个是实例方法.还有什么?

What distinguishes - and .difference() on sets? Obviously the syntax is not the same, one is a binary operator, the other is an instance method. What else?

s1 = set([1,2,3])
s2 = set([3,4,5])

>>> s1 - s2
set([1, 2])
>>> s1.difference(s2)
set([1, 2])

推荐答案

set.difference, set.union... 可以将 any iterable 作为第二个 arg 而两者都需要设置为使用-，输出没有区别.

set.difference, set.union... can take any iterable as the second arg while both need to be sets to use -, there is no difference in the output.

Operation      Equivalent       Result
s.difference(t) s - t   new set with elements in s but not in t

使用 .difference，您可以执行以下操作:

With .difference you can do things like:

s1 = set([1,2,3])

print(s1.difference(*[[3],[4],[5]]))

{1, 2}

使用 *(iterable,iterable) 语法创建集合时也更高效，因为您不创建中间集合，您可以看到一些比较 这里

It is also more efficient when creating sets using the *(iterable,iterable) syntax as you don't create intermediary sets, you can see some comparisons here

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