擅长:python、mysql、java
<p>因为列表只有两项,一个简单的<a href="https://docs.python.org/3/reference/expressions.html#conditional-expressions" rel="nofollow">conditional expression</a>就可以了:</p>
<pre><code>>>> a = ['rzz2', 'rzz3']
>>> b = 'rzz2'
>>> c = a[0] if a[0] != b else a[1]
>>> c
'rzz3'
>>>
</code></pre>
<p>性能方面,这是最快的解决方案:</p>
<pre><code>>>> from timeit import timeit
>>> a = ['rzz2', 'rzz3']
>>> b = 'rzz2'
>>> timeit('a[0] if a[0] != b else a[1]', 'from __main__ import a, b')
0.45458095931186787
>>> timeit('a[1 - a.index(b)]', 'from __main__ import a, b')
1.0331033692829674
>>> timeit('{b}.symmetric_difference(a)', 'from __main__ import a, b')
0.9464230789108647
>>> timeit('[i for i in a if i!=b][0]', 'from __main__ import a, b')
2.0873136110874384
>>>
</code></pre>