Python – 在 OrderedDict 的开头插入

给定一个有序字典，编写一个程序在有序字典的开头插入项目。
例子 -

Input: 
original_dict = {'a':1, 'b':2}
item to be inserted ('c', 3)

Output:  {'c':3, 'a':1, 'b':2}

Input: 
original_dict = {'akshat':1, 'manjeet':2}
item to be inserted ('nikhil', 3)

Output:  {'nikhil':3, 'akshat':1, 'manjeet':2}

以下是在有序字典的开头插入项目的各种方法。
方法 #1：使用 OrderedDict.move_to_end()

Python3

# Python code to demonstrate
# insertion of items in beginning of ordered dict
from collections import OrderedDict
 
# initialising ordered_dict
iniordered_dict = OrderedDict([('akshat', '1'), ('nikhil', '2')])
 
# inserting items in starting of dict
iniordered_dict.update({'manjeet':'3'})
iniordered_dict.move_to_end('manjeet', last = False)
 
# print result
print ("Resultant Dictionary : "+str(iniordered_dict))

输出：

Resultant Dictionary : OrderedDict([(‘manjeet’, ‘3’), (‘akshat’, ‘1’), (‘nikhil’, ‘2’)]) 
 

方法#2：使用朴素的方法
此方法仅适用于唯一键的情况

Python3

# Python code to demonstrate
# insertion of items in beginning of ordered dict
from collections import OrderedDict
 
# initialising ordered_dict
ini_dict1 = OrderedDict([('akshat', '1'), ('nikhil', '2')])
ini_dict2 = OrderedDict([("manjeet", '4'), ("akash", '4')])
 
# adding in beginning of dict
both = OrderedDict(list(ini_dict2.items()) + list(ini_dict1.items()))
 
# print result
print ("Resultant Dictionary :"+str(both))

输出：

Resultant Dictionary :OrderedDict([(‘manjeet’, ‘4’), (‘akash’, ‘4’), (‘akshat’, ‘1’), (‘nikhil’, ‘2’)])