We have covered lists and dictionaries so far. Lists and dictionaries cover many cases, but sometimes you only care about whether a value exists, not where it appears or how many times it shows up. This is where sets become useful. A set is a collection of unique values with no guaranteed order.
Understanding the Core Idea of Sets
A set stores items without duplicates. If the same value is added more than once, Python keeps only one copy.
So sets are greate for removing duplicates, provided that the order of the items is not important.
Sets are also great when you need to know if all items in a list are unique.
And if you want to ask about the common or unique values between two collections, you can use set operators. We are going to delve into this practice in a while.
So what makes sets stand out is that they do not support indexing. You cannot ask for the first or second element. Instead, you ask whether an element is present.
Creating Sets
You create a set using curly braces or the built in set() function.
Note: When you write empty curly braces like {}, Python will automatically generate a dictionary.
Methods for Sets
You can use the .add() method to include a new element in a set, simply by passing the element as an argument. If the element you’re trying to add is already present in the set, it won’t be added again
If you want to remove an element from a set, you can choose between two methods: .remove() or .discard(). Just pass the element you want to remove as an argument.
The .remove() method will throw a KeyError if the specified element is absent, whereas the .discard() method will simply do nothing.
We can remove all the elements from a set with the .clear() method.
Checking Membership Quickly
One of the most common uses of a set is membership testing. Checking whether a value exists in a set is fast and direct.
This pattern appears often in validation logic and filtering tasks.
Working With Set Operations
Sets support operations that compare groups of values. You can find shared items or items that appear only in one group.
The first result shows common elements. The second combines all unique elements.
Wrapping Up
Sets are designed to address a specific problem. When the order of elements is not a concern, sets provide a straightforward solution for checking duplicates.
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