在Python中根据索引查找列表项

Question

有没有其他更快的方法来找到特定位置的项目呢？

items = ['aaa','sss','ddd','fff','gggg','hhhh']
indices = [1,3,4]

My way: 
[items[i] for i in indices]

Answer 1

如果你一直在使用相同的索引，使用 operator.itemgetter 可能会更好：

getter = itemgetter(1,3,4)
desired = getter(items)

根据我简单的测试，itemgetter 的速度大约快了 2.5 倍（不过我没有测量一开始构建 getter 函数需要多长时间）。

>>> items = ['aaa','sss','ddd','fff','gggg','hhhh']
>>> indices = [1,3,4]
>>> from operator import itemgetter
>>> import timeit
>>> getter = itemgetter(*indices)
>>> def list_comp(items=items,indices=indices):
...     return [items[i] for i in indices]
... 
>>> timeit.timeit('getter(items)','from __main__ import getter,items')
0.2926821708679199
>>> timeit.timeit('list_comp()','from __main__ import list_comp')
0.7736802101135254
>>> getter(items)
('sss', 'fff', 'gggg')
>>> list_comp()
['sss', 'fff', 'gggg']