How to sort a list in Python?

Question

Jayant Kumar · Accepted Answer

Table of Contents
Introduction:
Sorting lists is a common task in Python programming, essential for organizing data and performing various operations. Python offers several methods for sorting lists, each with its unique characteristics. Understanding these methods helps you choose the right approach for your specific needs.
Using **sort()** Method
The sort() method sorts a list in place, meaning it modifies the original list and does not return a new list. This method sorts the list in ascending order by default, but you can customize the sorting order.
Syntax:
list.sort(key=None, reverse=False)

key: A function to specify a custom sort order (optional).
reverse: A boolean indicating whether to sort in descending order (optional).

Example:
numbers = [4, 2, 9, 1, 5]
numbers.sort()
print(numbers)  # Output: [1, 2, 4, 5, 9]

Sorting in Descending Order:
numbers = [4, 2, 9, 1, 5]
numbers.sort(reverse=True)
print(numbers)  # Output: [9, 5, 4, 2, 1]

Using **sorted()** Function
The sorted() function returns a new list that is sorted, leaving the original list unchanged. This function can be used with any iterable, not just lists.
Syntax:
sorted(iterable, key=None, reverse=False)

iterable: The collection to sort.
key: A function to specify a custom sort order (optional).
reverse: A boolean indicating whether to sort in descending order (optional).

Example:
numbers = [4, 2, 9, 1, 5]
sorted_numbers = sorted(numbers)
print(sorted_numbers)  # Output: [1, 2, 4, 5, 9]
print(numbers)         # Output: [4, 2, 9, 1, 5]  (original list unchanged)

Custom Sorting with **key** Parameter
You can customize the sort order using the key parameter with a function that returns a value used for sorting.
Example: Sorting by Absolute Values:
numbers = [-4, 2, -9, 1, 5]
sorted_numbers = sorted(numbers, key=abs)
print(sorted_numbers)  # Output: [1, 2, -4, 5, -9]

Sorting Lists of Tuples
When sorting lists of tuples, you can specify which element to sort by using the key parameter.
Example: Sorting by the Second Element of Tuples:
pairs = [(1, 'one'), (3, 'three'), (2, 'two')]
sorted_pairs = sorted(pairs, key=lambda x: x[1])
print(sorted_pairs)  # Output: [(1, 'one'), (2, 'two'), (3, 'three')]

Conclusion:
Python provides flexible methods for sorting lists and other iterables. The sort() method is ideal for in-place sorting, while the sorted() function is useful for creating new sorted lists without altering the original. Custom sorting can be achieved using the key parameter to tailor the sort order to specific needs. Understanding these methods enhances your ability to manage and organize data efficiently in Python.

How to sort a list in Python?

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Introduction:

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