Getting Started with Python Dictionaries: Build Your Data Storage Fortress

Basic knowledge of Python dictionary

python A dictionary is unordered, which means that the key-value pairs in it are not arranged in any particular order. A dictionary is a map type that allows you to associate a value with a key, where the key can be any immutable data type (such as string, number, or tuple) and the value can be of any type (Includes lists, dictionaries, or other mappings).

Creating and accessing dictionaries

To create a dictionary, use curly braces ({}) where key-value pairs are separated by colons (:). For example:

>>> my_dict = {"name": "John Doe", "age": 30, "city": "New York"}

To access a value in a dictionary, use square brackets ([]) followed by the dictionary's key. For example:

>>> my_dict["name"]
"John Doe"

Add and delete key-value pairs

To add key-value pairs to a dictionary, use the following syntax:

my_dict["new_key"] = "new_value"

To delete a key-value pair from a dictionary, use the following syntax:

del my_dict["key_to_delete"]

Common operations on dictionary

Python Dictionaries provide many useful methods for manipulating data. Some of the most common methods include:

• get() Method: Gets the value with the specified key, or returns None if the key does not exist.
• keys() Method: Returns a list of all keys in the dictionary.
• values() Method: Returns a list of all values ​​in the dictionary.
• items() Method: Returns a tuple list of key-value pairs in the dictionary.
• update() Method: Add the contents of another dictionary to the current dictionary.
• pop() Method: Removes and returns the value with the specified key from the dictionary.
• clear() Method: Clear all key-value pairs in the dictionary.

Dictionary application scenarios

• Caching: Dictionaries can be used to cache data to reduce the number of database queries or other time-consuming operations.
• Mapping table: Dictionaries can be used to implement mapping tables, where the keys are input values ​​and the values ​​are output values.
• Objects: Dictionaries can be used to represent objects, where the keys are the properties of the object and the values ​​are the values ​​of the properties.
• Configuration files: A dictionary can be used to store configuration files, where the keys are configuration options and the values ​​are the values ​​of the options.

Summarize

Python dictionaries are powerful tools for storing and managing data. It provides many useful methods to manipulate data and can be used in a variety of application scenarios. In this article, we introduced the basics of Python dictionaries and demonstrated through example code how to use dictionaries to store data.

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