Software Testing | How to implement dictionary key-value exchange, do you know it?

Introduction

In Python, a dictionary is a very useful data structure that stores data as key-value pairs and the keys must be unique. Sometimes, we may need to interchange the keys and values ​​of the dictionary to make it easier to find or manipulate data. This article will introduce in detail how to implement the interchange operation of dictionary key values ​​in Python.

Basic Concepts of Dictionary

First, let’s quickly review the basic concepts of Python dictionaries. A dictionary is a data structure composed of a series of key-value pairs, each of which consists of a key and an associated value. {}Dictionaries are created using curly braces , keys and values :​​are separated by colons, and key-value pairs are separated by commas,. Here is a simple dictionary example:

person = {
    
    
    "name": "John",
    "age": 30,
    "city": "Shanghai"
}

In this example, personthe dictionary contains three key-value pairs, namely "name", "age" and "city".

Implement dictionary key-value swap

To implement dictionary key-value exchange, there are several methods to choose from. Below we will introduce several common methods.

1. Method 1: Use dictionary derivation

Using dictionary comprehensions is a quick and concise way to exchange dictionary keys and values. Here is an example:

original_dict = {
    
    
    "name": "John",
    "age": 30,
    "city": "Shanghai"
}

flipped_dict = {
    
    value: key for key, value in original_dict.items()}

print(flipped_dict)

In this example, we first create a original_dictdictionary named . We then used dictionary comprehensions to create a new dictionary flipped_dictwhere the keys are original_dictthe values ​​in and the values ​​are original_dictthe keys in . Finally, we print flipped_dictand get the dictionary with the keys swapped. The printed results are as follows:

{
    
    'John': 'name', 30: 'age', 'Shanghai': 'city'}

2. use loop

Use a loop to traverse the original dictionary and exchange the positions of keys and values ​​one by one to implement key-value exchange in the dictionary. The code is as follows:

original_dict = {
    
    
    "name": "John",
    "age": 30,
    "city": "Shanghai"
}

flipped_dict = {
    
    }

for key, value in original_dict.items():
    flipped_dict[value] = key

print(flipped_dict)

In this example, we first create an empty dictionary flipped_dictand then use fora loop to iterate original_dictover the key-value pairs. In each iteration, we use original_dictthe value in as the key of the new dictionary and original_dictthe key in as the value of the new dictionary, thus achieving key-value exchange.

3. Use the zip function and decompress

Use the zip function and decompression to realize key-value exchange in the dictionary. The code is as follows:

original_dict = {
    
    
    "name": "John",
    "age": 30,
    "city": "Shanghai"
}

flipped_dict = dict(zip(original_dict.values(), original_dict.keys()))
print(flipped_dict)

------------
输出结果如下：
{
    
    'John': 'name', 30: 'age', 'Shanghai': 'city'}

Summarize

This article details how to implement dictionary key-value interchange operations in Python. We can choose to use dictionary comprehensions or loops or use to accomplish this task, depending on your preference and project needs. Either way, it makes it easier for you to work with data in the dictionary, making your code more readable and flexible.