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How to add to a set in Python

Unveiling Sets in Python

Sets in Python are akin to a real-life mathematical set. Imagine having a box filled with different items. Each item is unique, and there's no specific order in which they're arranged. A set in Python works just like this box. It is a collection of unique items, unordered and unindexed. As we dive in, we'll learn how to add items to our Python 'box'.

Creating a Set

The first step is creating a set. To create a set, we use curly braces {} or the set() function.

# Creating a set using curly braces
fruits = {"apple", "banana", "cherry"}

# Creating a set using the set() function
colors = set(["red", "green", "blue"])

This will output:

{'apple', 'banana', 'cherry'}
{'blue', 'red', 'green'}

Adding Items to a Set

Once we have our set, we can start adding items into it. We can add items to a set using the add() function. Let's add 'grape' to our fruits set.


This will output:

{'apple', 'banana', 'cherry', 'grape'}

What if I want to add multiple items?

For adding multiple items, Python provides the update() function. It takes an iterable (anything where we can loop over: lists, sets, tuples) as an input. Let's add 'mango' and 'orange' to our fruits set.

fruits.update(["mango", "orange"])

This will output:

{'cherry', 'apple', 'grape', 'banana', 'orange', 'mango'}

Handling Duplicates

Remember when I said sets are like a box of unique items? Here's where it comes into play. What happens when you try to add an item that's already in the set? Let's see.


This will still output:

{'cherry', 'apple', 'grape', 'banana', 'orange', 'mango'}

Even though we tried to add 'apple' again, Python ignored it because 'apple' is already in the fruits set. That's the beauty of sets - they automatically handle duplicates for us.

The Power of Python Sets

Sets might seem simple, but they're mighty. Let's say we have another set of fruits, tropical_fruits. We can use sets to quickly find common items (using intersection) or combine all items (using union). Let's see this in action:

tropical_fruits = {"banana", "mango", "pineapple"}

# Find common fruits
common_fruits = fruits.intersection(tropical_fruits)

# Combine all fruits
all_fruits = fruits.union(tropical_fruits)

This will output:

{'banana', 'mango'}
{'cherry', 'pineapple', 'apple', 'grape', 'banana', 'orange', 'mango'}

Conclusion: The Set Magic Trick

Congratulations! You've just learned how to add items to a set in Python. We started by creating a set, then we added items using the add() and update() functions. We also saw how Python sets automatically handle duplicate items.

Think of using sets like performing a magic trick. You have this magical box (your set), where you can throw in objects (your items) without worrying about arranging them, and duplicate items disappear like a puff of smoke. Even better, this magic box can instantly find common objects with another box or combine all objects into a bigger box.

Just like a good magic trick, the possibilities with Python sets are endless and exciting. So, roll up your sleeves, start experimenting and create your own magic with Python sets!