Python Tutorials
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Overview

A Python dictionary that contains other dictionaries as items is called a nested dictionary, and can be accessed just like a regular dictionary.

cars = {
    "car1" : {
        "model" : "Maserati",
        "year" : 2025
    },
    "car2" : {
        "model" : "Alfa Romeo",
        "year" : 2019
    },
    "car3" : {
        "model" : "Porsche",
        "year" : 2011
    }
}

print(cars)

Output:

{'car1': {'model': 'Maserati', 'year': 2025}, 'car2': {'model': 'Alfa Romeo', 'year': 2019}, 'car3': {'model': 'Porsche', 'year': 2011}}

Accessing a Nested Dictionary

cars = {
    "car1" : {
        "model" : "Maserati",
        "year" : 2025
    },
    "car2" : {
        "model" : "Alfa Romeo",
        "year" : 2019
    },
    "car3" : {
        "model" : "Porsche",
        "year" : 2011
    }
}

print(cars["car2"]["model"])

Output:

Alfa Romeo

Looping Through a Nested Dictionary

cars = {
    "car1" : {
        "model" : "Maserati",
        "year" : 2025
    },
    "car2" : {
        "model" : "Alfa Romeo",
        "year" : 2019
    },
    "car3" : {
        "model" : "Porsche",
        "year" : 2011
    }
}

for x, obj in cars.items():
    print(x)
    
    for y in obj:
        print(y + ':', obj[y])

Output:

car1
model: Maserati
year: 2025
car2
model: Alfa Romeo
year: 2019
car3
model: Porsche
year: 2011

Python Notes:

  • The most recent major version of Python is Python 3; however, Python 2 is still in use and quite popular, although not being updated with anything other than security updates
  • Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses
  • Python relies on indentation, using whitespace to define scope, such as the scope of loops, functions, and classes; other programming languages often use curly-brackets for this purpose
  • Python string methods return new values, and DO NOT change the original string
  • Python tuples are unchangeable after created (their items CANNOT be changed or re-ordered at a later point)
  • Python sets are unordered (may appear in random orders when called), unchangeable (the value of individual items cannot be changed after creation), unindexed (items cannot be referred to by index or key), and duplicates are NOT ALLOWED
  • As of v3.7, Python dictionaries are ordered and duplicates ARE ALLOWED; in v3.6 and earlier, dictionaries were unordered (did not have a defined order and could not be referred to using an index)
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We’d like to acknowledge that we learned a great deal of our coding from W3Schools and TutorialsPoint, borrowing heavily from their teaching process and excellent code examples. We highly recommend both sites to deepen your experience, and further your coding journey. We’re just hitting the basics here at 1SMARTchicken.