Python Dictionaries: Step-by-Step Tutorial for Beginners! | Lecture 13

In this video, we'll learn about dictionaries in Python. Dictionaries are a type of data structure that store data in key-value pairs. This means that each piece of data in a dictionary is associated with a unique key, and you can access the data by referring to its key.
We'll start by learning how to create dictionaries, and then we'll look at some examples of how to use them. We'll also see how to add, remove, and update items in a dictionary.
By the end of this video, you'll have a good understanding of how dictionaries work in Python, and you'll be able to use them to store and manipulate data in your programs.
Here are some examples of dictionaries in Python:
• A dictionary of words and their definitions:
Python
word_definitions = {
"hello": "greeting",
"goodbye": "farewell",
"computer": "electronic device",
}
• A dictionary of student names and their ages:
Python
student_data = {
"John": 25,
"Jane": 23,
"Mary": 21,
}
• A dictionary of countries and their capitals:
Python
country_capitals = {
"United States": "Washington, D.C.",
"United Kingdom": "London",
"France": "Paris",
}
• Creating dictionaries
Dictionaries can be created in a few different ways. One way is to use the dict() constructor, like this:
Python
word_definitions = dict([("hello", "greeting"), ("goodbye", "farewell"), ("computer", "electronic device")])

Another way to create a dictionary is to use the curly braces ({}) syntax, like this:
Python
student_data = {"John": 25, "Jane": 23, "Mary": 21}

• Accessing dictionary values
You can access the values in a dictionary by referring to their keys. For example, to get the definition of the word "hello", you would use the following code:
Python
print(word_definitions["hello"])
This will print the string "greeting".
• Adding, removing, and updating items in a dictionary
You can add, remove, and update items in a dictionary using the following methods:
• dict.update(): This method adds new items to a dictionary or updates existing items.
• dict.pop(): This method removes an item from a dictionary by its key.
• dict.setdefault(): This method sets a default value for a key in a dictionary if the key does not already exist.
For example, to add the word "world" to the dictionary of word definitions, you would use the following code:
Python
word_definitions.update({"world": "planet"})
To remove the word "goodbye" from the dictionary of student data, you would use the following code:
Python
student_data.pop("goodbye")
To set a default value of 0 for the age of a student named "Peter", you would use the following code:
Python
student_data.setdefault("Peter", 0)
• Built-in dictionary methods
There are a number of built-in methods that you can use to work with dictionaries in Python. Some of the most commonly used methods include:
• dict.keys(): This method returns a list of the keys in a dictionary.
• dict.values(): This method returns a list of the values in a dictionary.
• dict.items(): This method returns a list of key-value pairs in a dictionary.
• dict.get(): This method returns the value associated with a key in a dictionary. If the key does not exist, the method returns None.
For example, to get a list of the keys in the dictionary of word definitions, you would use the following code:
Python
print(word_definitions.keys())
This will print the list ["hello", "goodbye", "computer"].
Dictionaries are a powerful data structure that can be used to store and manipulate data in a variety of ways. They are particularly useful for storing data that is related to each other, such as the names and ages of students or the countries and their capitals.
Dictionaries are also very efficient, as they can be accessed and searched quickly. This makes them a good choice for storing data that needs to be accessed frequently.
I hope you enjoy this video and learn something new. If you do, please like, share, and subscribe to my channel for more Python tutorials. Thank you for watching!
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