Grokking Python Fundamentals
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Introduction to set in Python
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Python sets are collections that are both unordered and unindexed. They are used to store multiple items in a single variable. Sets are particularly useful for performing mathematical operations like unions, intersections, differences, and symmetric differences as only unique elements are stored.

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Defining a Set

Sets in Python can be defined by enclosing elements within curly braces {} or by using the built-in set() function. A set automatically removes any duplicate entries, keeping only unique items.

Example: Creating a set

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Explanation:

  • fruit_set is defined with duplicates, which are removed when the set is created, resulting in the set {'banana', 'cherry', 'apple'}.
  • color_set uses the set() function with a list that includes duplicates, which are also removed upon creation.

Updating a Set

Sets are mutable, meaning you can add items after the set has been created. The add() method adds a single element, and the update() method can add multiple elements (from another set, list, or any iterable).

Example: Adding elements to a set

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Explanation:

  • num_set is initialized with {1, 2, 3}.
  • num_set.add(4) adds the number 4 to the set.
  • num_set.update([5, 6]) adds both 5 and 6 to the set, demonstrating the use of update() for adding multiple items.

Removing Items from a Set

Items can be removed from a set using methods like remove() or discard(). While remove() will raise an error if the item does not exist, discard() will not.

Example: Removing elements from a set

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Explanation:

  • my_set starts with {10, 20, 30, 40, 50}.
  • my_set.remove(10) removes 10 from the set.
  • my_set.discard(60) attempts to discard 60. Since 60 is not in the set, nothing happens and no error is thrown.

Copying a Set

To make a copy of a set, you can use the copy() method. This creates a new set that is a copy of the original, allowing you to modify one set without affecting the other.

Example: Copying a set

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Explanation:

  • original_set contains {'a', 'b', 'c'}.
  • copied_set = original_set.copy() creates a copy of original_set, resulting in another set with the same elements.

Looping Through a Set

Although sets are unordered, you can still loop through the set items using a for loop. This can be useful for applying operations to each item.

Example: Iterating over a set.

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Explanation:

  • char_set is initialized with the characters {'X', 'Y', 'Z'}.
  • The for loop iterates through each element in the set, printing them one by one. The output order may vary due to the unordered nature of sets.

This introduction to Python sets covers the basics of creating and manipulating sets, including adding and removing items, copying sets, and iterating over them. These operations form the foundation of set usage in Python, suitable for managing unique collections of items efficiently.

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