如何保持字典爲了荏苒

Question

字典後保持正確的順序時，大約有1,2或3個單元只

>>> a = ["dorian", "strawberry", "apple"] 
>>> b = ["sweet", "delicious", "tasty"] 
>>> c = dict(zip(a, b)) 
>>> c 
{'dorian': 'sweet', 'strawberry': 'delicious', 'apple': 'tasty'} 

但是，當有超過3元，訂單被打破

>>> a = ["dorian", "strawberry", "apple", "coconut"] 
>>> b = ["sweet", "delicious", "tasty", "yum"] 
>>> c = dict(zip(a, b)) 
>>> c 
{'strawberry': 'delicious', 'coconut': 'yum', 'dorian': 'sweet', 'apple': 'tasty'} 

任何人都可以請解釋爲什麼發生這種情況？謝謝

Answer 1

Python字典不保留任何順序，您應該使用OrderedDict。

In [7]: from collections import OrderedDict as od 

In [8]: a = ["dorian", "strawberry", "apple"] 

In [9]: b = ["sweet", "delicious", "tasty"] 

In [10]: dic=od(zip(a,b)) 

In [11]: dic 
Out[11]: OrderedDict([('dorian', 'sweet'), ('strawberry', 'delicious'), ('apple', 'tasty')]) 

Answer 2

Python dicts are unordered。改爲使用collections.OrderedDict。

from collections import OrderedDict as odict 

# ... 
c = odict(zip(a, b)) 

Answer 3

字典是地圖數據結構。你永遠不能保證線性的順序。犧牲這個你可以在底層實現中獲得速度。