Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Python program to print duplicates from a list of integers?
We will display duplicates from a list of integers in this article. The list is can be written as a list of comma-separated values (items) between square brackets. Important thing about a list is that the items in a list need not be of the same type
Let’s say we have the following input list −
[5, 10, 15, 10, 20, 25, 30, 20, 40]
The output display duplicate elements −
[10, 20]
Print duplicates from a list of integers using for loop
We will display the duplicates of a list of integer using a for loop. We will loop around and compare each element of the list with another to find a match. After that, if a match is found, that would mean it is a duplicate and the same gets displayed −
Example
# Create a List myList = [5, 10, 15, 18, 20, 25, 30, 30, 40, 50, 50, 50] dupItems = [] uniqItems = {} # Display the List print("List = ",myList) for x in myList: if x not in uniqItems: uniqItems[x] = 1 else: if uniqItems[x] == 1: dupItems.append(x) uniqItems[x] += 1 print("Duplicate Elements = ",dupItems)
Output
List = [5, 10, 15, 18, 20, 25, 30, 30, 40, 50, 50, 50] Duplicate Elements = [30, 50]
Print Duplicates from a list of integers using the Counter
We will display the duplicates from a list of integer using the Counter. The Counter comes from the Collections module. This module implements specialized container datatypes providing alternatives to Python’s general purpose built-in containers, dict, list, set, and tuple −
Example
from collections import Counter # Create a List myList = [5, 10, 15, 10, 20, 25, 30, 20, 40] # Display the List print("List = ",myList) # Get the Count of each elements in the list d = Counter(myList) # Display the Duplicate elements res = list([item for item in d if d[item]>1]) print("Duplicate Elements = ",res)
Output
List = [5, 10, 15, 10, 20, 25, 30, 20, 40] Duplicate Elements = [10, 20]
Print Duplicates from a list of integers using the List Comprehension with Set
The syntax of List Comprehension is the following −
[expression for item in list]
Let us now see the example −
Example
# Create a List myList = [5, 10, 15, 10, 20, 25, 30, 20, 40] # Display the List print("List = ",myList) # Display the duplicate elements print(list(set([a for a in myList if myList.count(a) > 1])))
Output
List = [5, 10, 15, 10, 20, 25, 30, 20, 40] [10, 20]
2K+ Views
