Mastering Nested Dictionaries in Python

Nested dictionaries in Python are dictionaries that contain other dictionaries as their values, enabling the organization of complex data in a hierarchical format.

Key Concepts

• Dictionary: A collection of key-value pairs, defined using curly braces {}. Each key must be unique.
• Nested Dictionary: A dictionary where the value of a key can also be another dictionary.

Creating Nested Dictionaries

You can create a nested dictionary by defining a dictionary within another dictionary.

Example:

student = {
    "name": "Alice",
    "age": 21,
    "courses": {
        "course1": {
            "name": "Mathematics",
            "grade": "A"
        },
        "course2": {
            "name": "Physics",
            "grade": "B"
        }
    }
}

Accessing Nested Dictionary Values

To access values in a nested dictionary, you can chain the keys.

Example:

print(student["courses"]["course1"]["name"])  # Output: Mathematics
print(student["courses"]["course2"]["grade"])  # Output: B

Modifying Nested Dictionaries

You can easily modify values in a nested dictionary by using the appropriate keys.

Example:

student["courses"]["course1"]["grade"] = "A+"
print(student["courses"]["course1"]["grade"])  # Output: A+

Adding New Entries

New key-value pairs can be added to the nested dictionary just like with regular dictionaries.

Example:

student["courses"]["course3"] = {
    "name": "Chemistry",
    "grade": "B+"
}

Summary

• Nested dictionaries provide a structured way to store related data.
• Using standard dictionary operations, you can create, access, modify, and add entries in nested dictionaries.
• This feature is particularly useful for managing complex data structures, such as configurations and database records.

By mastering nested dictionaries, you can effectively manage and manipulate hierarchical data in your Python programs.