Get Least Common Element in a List in Python

In this article, we will discuss different ways to get the least common element in a Python List.

Table Of Contents

Get Least Common Value in List

Import Counter class from collections module. The Counter class is a Dictionay subclass, and it is used for counting hashable items. Inside a Counter object, elements are stored as dictionary keys and their counts are stored as dictionary values. We can pass the list object to Counter() function, to get a Counter object. It will have all the unique elements of list as keys, and thier occurrence count as values.

Then call the most_common(n) function of Counter. It returns a list of the n most common elements and their counts from the Counter object. If n is not provided, then it returns all the unique elements in list, and their occurrence count in a decreading order of occurrence count. The last value in this list is the least common value, and its occurrence count. Let’s see an example,

from collections import Counter

listOfNums = [11, 15, 12, 11, 15, 16, 12, 11, 19, 15, 19, 16, 11, 12, 16, 12, 15]

# Get least common value, and its occurrence count
leastCommonValue , frequency = Counter(listOfNums).most_common()[-1]

print('Least Common Value : ', leastCommonValue)
print('Occurrence Count of Least Common Value : ', frequency)

Output:

Advertisements
Least Common Value :  19
Occurrence Count of Least Common Value :  2

The last common element in list was 19, with occurrence

Get N Least Common Values in List

To get the N least common values from a list, we need to pass the select the last N elements from list returned by most_common(). Let’s see an example,

from collections import Counter

listOfNums = [11, 15, 12, 11, 15, 16, 12, 11, 19, 15, 19, 16, 11, 12, 16, 12, 15]

# Get two least common values in list
values = Counter(listOfNums).most_common()[-2 : ]

for (value , frequency )in values:
    print('Value : ', value, ' :: Occurrence Count : ', frequency) 

Output:

Value :  16  :: Occurrence Count :  3
Value :  19  :: Occurrence Count :  2

We printed the two least common elements of list, along with thier occurrence count.

Summary

We learned how to get the least common value in a list in Python.

Pandas Tutorials -Learn Data Analysis with Python

   

Are you looking to make a career in Data Science with Python?

Data Science is the future, and the future is here now. Data Scientists are now the most sought-after professionals today. To become a good Data Scientist or to make a career switch in Data Science one must possess the right skill set. We have curated a list of Best Professional Certificate in Data Science with Python. These courses will teach you the programming tools for Data Science like Pandas, NumPy, Matplotlib, Seaborn and how to use these libraries to implement Machine learning models.

Checkout the Detailed Review of Best Professional Certificate in Data Science with Python.

Remember, Data Science requires a lot of patience, persistence, and practice. So, start learning today.

Join a LinkedIn Community of Python Developers

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to Top