Dicionário Python: Guia de Referência Rápida
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Python Dictionary Cheat Sheet
Introduction
Welcome to the Python Dictionary Cheat Sheet! This guide will provide you with a comprehensive overview of dictionaries in Python, along with detailed, step-by-step examples, and explanations. Whether you’re new to Python or a seasoned developer, this cheat sheet will help you understand and utilize dictionaries effectively.
What is a Dictionary?
A dictionary in Python is an unordered collection of key-value pairs. It allows you to store, retrieve, and manipulate data using a unique key as an identifier. Dictionaries are mutable objects, meaning you can modify them after creation. They are denoted by curly braces {}, with each key-value pair separated by a colon :.
Creating a Dictionary
To create a dictionary in Python, you can use the curly braces {} and provide key-value pairs separated by a colon :. Here’s an example:
my_dict = {'name': 'John', 'age': 25, 'city': 'New York'}Accessing Values in a Dictionary
You can access the values in a dictionary by using the key associated with the value. Here are a few methods to retrieve values from a dictionary:
- Using square brackets
[]and the key:
name = my_dict['name']- Using the
get()method:
age = my_dict.get('age')- Using the
keys()andvalues()methods to access all keys and values:
keys = my_dict.keys()values = my_dict.values()Modifying Dictionary Values
Dictionaries allow you to modify the values associated with a particular key. Here’s how you can do it:
my_dict['name'] = 'Jane'Adding and Removing Key-Value Pairs
To add a new key-value pair to a dictionary, you can assign a value to a new key:
my_dict['city'] = 'San Francisco'To remove a key-value pair from a dictionary, you can use the del keyword:
del my_dict['age']Dictionary Methods
Python provides various built-in methods for dictionaries. Here are a few commonly used ones:
| Method | Description |
|---|---|
clear() | Removes all key-value pairs from the dictionary |
copy() | Returns a shallow copy of the dictionary |
update() | Updates the dictionary with the key-value pairs from another dictionary |
pop() | Removes and returns the value for a specified key |
items() | Returns a view object that contains the key-value pairs |
Dictionary Comprehension
Python also supports dictionary comprehension, which allows you to create dictionaries in a concise manner. Here’s an example:
my_dict = {x: x**2 for x in range(5)}Conclusion
In this Python Dictionary Cheat Sheet, we covered the basics of dictionaries, including creating dictionaries, accessing values, modifying values, adding and removing key-value pairs, and using built-in methods. We also explored dictionary comprehension as a powerful way to create dictionaries. With this knowledge, you’ll be able to effectively utilize dictionaries in your Python projects.
Remember, dictionaries are versatile data structures that provide efficient key-value mapping, making them an essential tool in your Python programming journey!
Happy coding with Python!
