python查找指定列表中的項目

Question

是否有任何其他更快的方式來查找索引位置處的項目。

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

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

Answer 1

如果你反覆使用同一指標，你可能會operator.itemgetter做的更好：

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

據我簡單的基準，itemgetter約2.5倍更快（但我沒有」 t時間實際構造getter函數需要多長時間）。

>>> 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']