How to Sort a List of Lists by a Specific Index in Python?

Sorting a List of Lists by an Index Using Python

Sorting a list of lists by a specific index of the inner list can be achieved in Python using the itemgetter operator from the operator module.

Problem Statement:

Given a list of lists, where each inner list contains three elements: two integers and a string, the objective is to sort the outer list based on the string value in the inner lists.

Solution:

The itemgetter operator can be applied to a list of lists using the key argument of the sorted function. This allows for specifying the index of the inner list that should be used for sorting.

Python Code:

>>> from operator import itemgetter
>>> L = [[0, 1, 'f'], [4, 2, 't'], [9, 4, 'afsd']]
>>> sorted(L, key=itemgetter(2))
[[9, 4, 'afsd'], [0, 1, 'f'], [4, 2, 't']]

Explanation:

In the above code:

• from operator import itemgetter imports the itemgetter operator.
• L is the provided list of lists.
• sorted(L, key=itemgetter(2)) calls the sorted function to sort the list L. The key argument specifies the itemgetter(2) operator, which indicates that the string value (index 2) of each inner list should be used for sorting.

Alternatively, a lambda function can be used instead of itemgetter:

>>> sorted(L, key=lambda x: x[2])
[[9, 4, 'afsd'], [0, 1, 'f'], [4, 2, 't']]

However, the itemgetter approach is generally more efficient in this scenario.

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