Python|反转字典映射的方法

字典是一个无序、可变和索引的集合。在Python中，字典是用大括号编写的，它们有键和值。它广泛用于日常编程、Web 开发和机器学习。
让我们讨论几种反转字典映射的方法。
方法#1：使用字典理解。

# Python code to demonstrate
# how to invert mapping 
# using dict comprehension
  
# initialising dictionary
ini_dict = {101: "akshat", 201 : "ball"}
  
# print initial dictionary
print("initial dictionary : ", str(ini_dict))
  
# inverse mapping using dict comprehension
inv_dict = {v: k for k, v in ini_dict.items()}
  
# print final dictionary
print("inverse mapped dictionary : ", str(inv_dict))

输出：

initial dictionary :  {201: 'ball', 101: 'akshat'}
inverse mapped dictionary :  {'ball': 201, 'akshat': 101}

方法 #2：使用dict.keys()和dict.values()

# Python code to demonstrate
# how to invert mapping 
# using zip and dict functions
  
# initialising dictionary
ini_dict = {101: "akshat", 201 : "ball"}
  
# print initial dictionary
print("initial dictionary : ", str(ini_dict))
  
# inverse mapping using zip and dict functions
inv_dict = dict(zip(ini_dict.values(), ini_dict.keys()))
  
# print final dictionary
print("inverse mapped dictionary : ", str(inv_dict))

输出：

initial dictionary :  {201: 'ball', 101: 'akshat'}
inverse mapped dictionary :  {'ball': 201, 'akshat': 101}

方法 #3：使用map()和反转

# Python code to demonstrate
# how to invert mapping 
# using map and reversed
  
# initialising dictionary
ini_dict = {101: "akshat", 201 : "ball"}
  
# print initial dictionary
print("initial dictionary : ", str(ini_dict))
  
# inverse mapping using map and reversed
inv_dict = dict(map(reversed, ini_dict.items()))
  
# print final dictionary
print("inverse mapped dictionary : ", str(inv_dict))

输出：

initial dictionary :  {201: 'ball', 101: 'akshat'}
inverse mapped dictionary :  {'akshat': 101, 'ball': 201}

方法 #4：使用 lambda

# Python code to demonstrate
# how to invert mapping 
# using lambda
  
# initialising dictionary
ini_dict = {101 : "akshat", 201 : "ball"}
  
# print initial dictionary
print("initial dictionary : ", str(ini_dict))
  
# inverse mapping using lambda
lambda ini_dict: {v:k for k, v in ini_dict.items()}
  
# print final dictionary
print("inverse mapped dictionary : ", str(ini_dict))

输出：

initial dictionary :  {201: 'ball', 101: 'akshat'}
inverse mapped dictionary :  {201: 'ball', 101: 'akshat'}