Sorting Lists in Python: A Comprehensive Guide

Sorting data is a fundamental operation in programming. In Python, the sort() method provides an efficient way to organize list elements either alphabetically or numerically, in both ascending and descending order. This guide, brought to you by Devyra, walks you through various sorting techniques using practical examples.

Sorting Lists Alphanumerically

By default, Python’s sort() method arranges items in ascending order, whether they are strings or numbers.

Example: Alphabetical Sorting

thislist = ["orange", "mango", "kiwi", "pineapple", "banana"]
thislist.sort()
print(thislist)

Example: Numerical Sorting

thislist = [100, 50, 65, 82, 23]
thislist.sort()
print(thislist)

Sorting in Descending Order

To sort in descending order, use the keyword argument reverse=True with the sort() method.

Example: Descending String Sort

thislist = ["orange", "mango", "kiwi", "pineapple", "banana"]
thislist.sort(reverse=True)
print(thislist)

Example: Descending Numerical Sort

thislist = [100, 50, 65, 82, 23]
thislist.sort(reverse=True)
print(thislist)

Custom Sorting with a Function

You can define a custom sorting rule using the key= parameter. The function should return a value that determines the order of elements.

Example: Sort by Proximity to 50

def myfunc(n):
    return abs(n - 50)

thislist = [100, 50, 65, 82, 23]
thislist.sort(key=myfunc)
print(thislist)

Case-Insensitive Sorting

By default, sorting is case-sensitive in Python, which means capital letters come before lowercase ones. To sort regardless of case, use str.lower as a key function.

Example: Default Case-Sensitive Sort

thislist = ["banana", "Orange", "Kiwi", "cherry"]
thislist.sort()
print(thislist)

Example: Case-Insensitive Sort

thislist = ["banana", "Orange", "Kiwi", "cherry"]
thislist.sort(key=str.lower)
print(thislist)

Reversing a List

To reverse the elements in their current order—without sorting—you can use the reverse() method.

Example: Reverse a List

thislist = ["banana", "Orange", "Kiwi", "cherry"]
thislist.reverse()
print(thislist)

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