【collections】Python中的OrderDict

1. 什么是OrderedDict

其實很簡單OrderedDict是Python中一個字典dict的變體，它可以按照元素添加的順序來保持鍵值對（key-value pair）的順序。與普通的字典相比，OrderedDict 保持了元素的添加順序。這在需要按照添加的順序訪問鍵值對時非常有用。

2. Toy Code

from collections import OrderedDict# 創建一個空的 OrderedDict
ordered_dict = OrderedDict()# 添加鍵值對
ordered_dict['one'] = 1
ordered_dict['two'] = 2
ordered_dict['three'] = 3normal_dict = {}
normal_dict['one'] = 1
normal_dict['two'] = 2
normal_dict['three'] = 3print(ordered_dict)
print(normal_dict)
# 遍歷 OrderedDict 的鍵值對（按照添加的順序）
for key, value in ordered_dict.items():print(key, value)for key, value in normal_dict.items():print(key, value)

結果如下

OrderedDict([('one', 1), ('two', 2), ('three', 3)])
{'one': 1, 'two': 2, 'three': 3}
one 1
two 2
three 3
one 1
two 2
three 3