Python | Check if any element occurs n times in given list

Last Updated : 08 Sep, 2020

Given a list, the task is to find whether any element occurs ‘n’ times in given list of integers. It will basically check for the first element that occurs n number of times.
Examples:

Input: l =  [1, 2, 3, 4, 0, 4, 3, 2, 1, 2], n = 3
Output :  2

Input: l =  [1, 2, 3, 4, 0, 4, 3, 2, 1, 2, 1, 1], n = 4
Output :  1

Below are some methods to do the task in Python –
Method 1: Using Simple Iteration and Sort

Python3

# Python code to find occurrence of any element
# appearing 'n' times
 
# Input Initialisation
input = [1, 2, 3, 0, 4, 3, 4, 0, 0]
 
# Sort Input
input.sort()
 
# Constants Declaration
n = 3
prev = -1
count = 0
flag = 0
 
# Iterating
for item in input:
    if item == prev:
        count = count + 1
    else:
        count = 1
    prev = item
     
    if count == n:
        flag = 1
        print("There are {} occurrences of {} in {}".format(n, item, input))
        break
 
# If no element is not found.
if flag == 0:
    print("No occurrences found")

Output :

There are 3 occurrences of 0 in [0, 0, 0, 1, 2, 3, 3, 4, 4]

Method 2: Using Count

Python3

# Python code to find occurrence of any element
# appearing 'n' times
 
# Input list initialisation
input = [1, 2, 3, 4, 0, 4, 3, 4]
 
# Constant declaration
n = 3
 
# print
print("There are {} occurrences of {} in {}".format(input.count(n), n, input))

Output :

There are 2 occurrences of 3 in [1, 2, 3, 4, 0, 4, 3, 4]

Method 3: Using defaultdict
We first populate item of list in a dictionary and then we find whether count of any element is equal to n.

Python3

# Python code to find occurrence of any element
# appearing 'n' times
 
# importing
from collections import defaultdict
 
# Dictionary declaration
dic = defaultdict(int)
 
# Input list initialisation
Input = [9, 8, 7, 6, 5, 9, 2]
 
# Dictionary populate
for i in Input:
    dic[i]+= 1
 
# constant declaration
n = 2
flag = 0
 
# Finding from dictionary
for element in Input:
    if element in dic.keys() and dic[element] == n:
        print("Yes, {} has {} occurrence in {}.".format(element, n, Input))
        flag = 1
        break
 
# if element not found.
if flag == 0:
    print("No occurrences found")

Output :

Yes, 9 has 2 occurrence in [9, 8, 7, 6, 5, 9, 2]

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes

Related Articles

Python3

Python3

Python3