Write a Python program to display frequencies of all the elements of a list

List frequency of elements in Python

PythonServer Side ProgrammingProgramming

In this article, we are going to learn how to find the frequency of elements in a list. We can solve the problem in different ways. Let's see two of them.

Table of Contents Show

List frequency of elements in Python
Python: Get the frequency of the elements in a list
Counting the frequencies in a list using dictionary in Python
2. Python program to find the frequency of each element in the array
Counting the frequencies in a list using dictionary in Python
“count frequency of elements in list python” Code Answer’s
Python answers related to “count frequency of elements in list python”
Python queries related to “count frequency of elements in list python”
Count frequency of elements in a list using for loop

Follow the below steps to write the code.

Initialize the list with elements and an empty dictionary.
Iterate over the list of elements.
- Check whether the element is present in the dictionary or not.
- If the element is already present in the dictionary, then increase its count.
- If the element is not present in the dictionary, then initialize its count with 1.
Print the dictionary.

Python: Get the frequency of the elements in a list

Last update on April 13 2021 05:36:53 (UTC/GMT +8 hours)

Counting the frequencies in a list using dictionary in Python

Given an unsorted list of some elements(may or may not be integers), Find the frequency of each distinct element in the list using a dictionary.
Example:

Input : [1, 1, 1, 5, 5, 3, 1, 3, 3, 1, 4, 4, 4, 2, 2, 2, 2] Output : 1 : 5 2 : 4 3 : 3 4 : 3 5 : 2 Explanation : Here 1 occurs 5 times, 2 occurs 4 times and so on...

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The problem can be solved in many ways. A simple approach would be to iterate over the list and use each distinct element of the list as a key of the dictionary and store the corresponding count of that key as values. Below is the Python code for this approach:

Python

# Python program to count the frequency of 
# elements in a list using a dictionary

def CountFrequency(my_list):

# Creating an empty dictionary

freq = {}

for item in my_list:

if (item in freq):

freq[item] += 1

else:

freq[item] = 1

for key, value in freq.items():

print ("% d : % d"%(key, value))
# Driver function

if __name__ == "__main__":

my_list =[1, 1, 1, 5, 5, 3, 1, 3, 3, 1, 4, 4, 4, 2, 2, 2, 2]

CountFrequency(my_list)

Output: 1 : 5 2 : 4 3 : 3 4 : 3 5 : 2

Time Complexity:O(N), where N is the length of the list.

Alternative way: An alternative approach can be to use the list.count() method.

Python

# Python program to count the frequency of
# elements in a list using a dictionary

def CountFrequency(my_list):

# Creating an empty dictionary

freq = {}

for items in my_list:

freq[items] = my_list.count(items)

for key, value in freq.items():

print ("% d : % d"%(key, value))
# Driver function

if __name__ == "__main__":

my_list =[1, 1, 1, 5, 5, 3, 1, 3, 3, 1, 4, 4, 4, 2, 2, 2, 2]

CountFrequency(my_list)

Output: 1 : 5 2 : 4 3 : 3 4 : 3 5 : 2

Time Complexity:O(N2), where N is the length of the list. The time complexity list.count() is O(N) alone, and when used inside loop it will become O(N2).

Alternative way:An alternative approach can be to use the dict.get() method. This makes the program much more shorter and makes understand how get method is useful instead of if…else.

Python

# Python program to count the frequency of
# elements in a list using a dictionary

def CountFrequency(my_list):

# Creating an empty dictionary

count = {}

for i in [1, 1, 1, 5, 5, 3, 1, 3, 3, 1 ,4, 4, 4, 2, 2, 2, 2]:

count[i] = count.get(i, 0) + 1

return count
# Driver function

if __name__ == "__main__":

my_list =[1, 1, 1, 5, 5, 3, 1, 3, 3, 1, 4, 4, 4, 2, 2, 2, 2]

print(CountFrequency(my_list))

Output: {1: 5, 5: 2, 3: 3, 4: 3, 2: 4}

Related Article :
Count frequencies of all elements in array in Python using collections module

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

Article Tags :

Python

frequency-counting

Python dictionary-programs

python-dict

python-list

Practice Tags :

python-dict

python-list

Read Full Article

2. Python program to find the frequency of each element in the array

In this program, we have an array of elements to count the occurrence of its each element. One of the approaches to resolve this problem is to maintain one array to store the counts of each element of the array. Loop through the array and count the occurrence of each element as frequency and store it in another array fr.

In the given array, 1 has appeared two times, so its frequency is 2, and 2 has appeared four times so have frequency 4 and so on.

ALGORITHM:

STEP 1: Declare and initialize an array arr.
STEP 2: Declare another array fr with the same size of array arr. It is used to store the frequencies of elements present in the array.
STEP 3: Variable visited will be initialized with the value -1. It is required to mark an element visited that is, it helps us to avoid counting the same element again.
STEP 4: The frequency of an element can be counted using two loops. One loop will be used to select an element from an array, and another loop will be used to compare the selected element with the rest of the array.
STEP 5: Initialize count to 1 in the first loop to maintain a count of each element. Increment its value by 1 if a duplicate element is found in the second loop since we have counted this element and didn't want to count it again. Mark this element as visited by setting fr[j] = visited. Store count of each element to fr.
STEP 6: Finally, print out the element along with its frequency.

PROGRAM:

Output:

---------------------------------------- Element | Frequency ---------------------------------------- 1 | 2 2 | 4 8 | 1 3 | 1 5 | 1 ----------------------------------------

Counting the frequencies in a list using dictionary in Python

In this tutorial, you will learn to write a program in Python that will count the frequency of elements in a list using a dictionary. For a given list with multiple elements, we have to count the occurrence of each element in the list and display it as output. This can be done by creating a dictionary and using some built-in methods which will be discussed below.

Look at the input-output format to understand better.

Input: ['a', 'a', 'a', 'b','b']

Output: {'a': 3, 'b': 2}

To solve this problem we can follow these approaches-

by iterating over the list and counting frequency
using list.count() method
using dict.get() method

“count frequency of elements in list python” Code Answer’s

how to get frequency of each elements in a python list

python by Frantic Ferret on May 24 2021 Comment

Source: buggyprogrammer.com

python count the frequency of words in a list

python by Andrea Perlato

on Feb 25 2021 Donate Comment

Source: stackoverflow.com

list count frequency python

python by Cheerful Cormorant on Jul 15 2020 Comment

Source: stackoverflow.com

Add a Grepper Answer

numpy array count frequency
how to find no of times a elements in list python
python find number of occurrences in list
count occurrence in array python
python count number of unique elements in a list

find frequency of numbers in list python
count how many times a value shows in python list
count different values in list python
how to create frequency table in python
python count appearances in list

find all occurrences of an element in a list python
count number of occurrences of all elements in list python
count number of each item in list python

count frequency of elements in list python
get frequency of elements in list python
how to count frequency of elements in a list in python
frequency in list python
python frequency count of list
frequency of elements in list python
python get frequency of elements in list
count frequency of words in list python
frequency count list python
python get frequency of items in list
python count frequency of items in list
how to count word frequency in python
freq count in python
count the frequency of each element of an array python
count frequency of each element in a list python
frequency of elements in an array python
how to count frequency of list of lists python
how to check frequency of elements in list in python
frequency of list in python
frequency element python list
create frequency of values in a list python
how to count frequency of all elements in a list
how to count frequency of elements in a list in python 3
python calculate frequency in list
count frequency of item in list python
count frequency of numbers in list python
counting frequency of an element in python
python dictionary for frequency
python count word frequency
count object frequency in list
count frequency of element in list using list.count python using for loop
find the frequency of given numbers in list python
python count number frequency in list
how to find frequency of each element in array in python
number frequency counter python
list get frequency of item python
count frequency of elements in many lists
get the frequency of the elements in a list
frequency count in python
how to find the frequency of an element in a list in python
element frequency list python
how to get the frequency of values in a list python
python word frequency in a list
counting the frequency of elements in a list using a dictionary in python
how to count the frequency of elements ina alist in pyhton
fastest way to get the frequency of numbers of a list
how to find frequency of words in python
frequency of list of list python
find frequency of a word in python
frequency of an element in a list python
check word frequency in a list python
frequency of a word in a list python
calculate the frequency of occurrence of each character/integer in that list(count
count frequency of wods in list
count frequency of words in sentence python
python frequency table from list
counting the frequencies in a list using dictionary in python in anseding order
how to count the frequency of a word in python
frequency of array elements python
how to count a frequency of word in python
how to count frequency of letters in a word in python
how to get frequency of each elements in a python list
how to get frequency of each elements in a python
counting the most frequency of words in coulm python
get frequency of elements in array python
python count the frequency of words in a list and sort by value
find the frequency of elements in a list in python
how to find the frequency of an item in a list python
how to find the frequency of a number in a list in python
get the frequency of the elements in a list app no code
python list get element frequency
frequency in lists in python
python program to get the frequency of the elements in a given list of lists in python
frequency of a item python
list method to find frequency of an element in a list
count the frequency of a value in a list python
how to find frequency of an item in a python list
count frequency of each element in an list using python
frequency of values in list python np
frequency of element in list python
frequency of a elemnt in list in python
get the frequency of a element in an array python
find frequency of item in list python
how to get frequency of elements by index in python
calculate the frequency of each element in a list
function for frequency of occurence of a item in a list in python
return frequency of item in list python
how to find frequency of all elements in list in python
find frequency of list python map
find the frequency of each element in the list
list elements frequency python
how to find the frequency of a number in an array in python
find out the frequency of a element in python
frequency of an element in a list of lists python
frequency of a word in a list ython
python count frequency in dictionary
freqency in python
how to get frequency of list in python
count the frequency of all the list elements and store the frequency in a dictionary in python
how to count key frequency in python
python find frequency of element in list
write a python program to get the frequency of the elements in a list
count word frequency python
python frequency counter of list
frequency count dictionary python
count character frequency python
frequency of the elements in a list
counting frequnecies of elements in a list in python
how to count frequency of item in list python
find frequency of elements in python ,lst
frequency of output value python
frequency count in list in python using function
use switch to count frequency python
freuency of a list python
how to count the frequency of a value in python
python list count equal elements
use dictionary to count frequency python
frequency table from list python
display frequencies of words in an array using dictionaries python
counting the frequencies in a list using dictionary in python
python count number frequency
finding elements with equal frequency as its value in list python
key frequency python
to count the frequency of each word in the given string. python
count and frequency of list on words in panda
word frequency in a list python
create frequency of words in list python
count the frequency of words in python
count frequency of elements in series python
plot of values frequency in list python
count frequency of string in list python
word frequency counter in a list return list python
count frequency of each element in a string python
count frequency of words in list of string python
python count frequency of each word
python how to count the frequency of a specific word in a list
find the frequency of word python
frequency table from list counter python
list of frequency python
python frequency counter list
a list that count frequency of a element in python
frequency of list items python
python count element frequency in list
frequency on list python
count frequency of the values in a list
count frequency of element in adjacency list
find frequency of number in adjacency list python
python count list elements frequency
python check frequency of numbers
python count item frequency in list
fastest to count frequency in list oyhton
how to count frequency in list python

python count frequency in list
frequency of element in list python
wap to count frequency of a given element in a list of numbers.
how to count the frequency of elements in a list in python
python list frequency count
count frequency of an element in list python
maximum frequency python using dictionary
python get frequency of list
count the frequency of each element of a list python
frequency of numbers in list python
count frequency of element in list python
python frequency of number in list
python frequency of elements in list
counting the frequency of elements in a list
python count frequency of numbers in a list
find frequency of elements in list python
python count list frequency
check frequency of element in list python
find frequency of numbers in list python
python list group by count
how to find frequency of a number in a list in python
how to find frequency of a value in list in python
frequency in a list python
count frequency of a list python
python count frequency in array
list element frequency python
count frequency of one element in list python
frequency of list elements python
finding the frequency of elements in an array using python
python - count frequency of specific words in a text
frequency of word in list python
calculate frequency in python in a list
do not print the frequency of numbers in python
get frequency of value in list python
get frequency of elements in list pandas
how to find the frequency of each element in an array in python
how to count the frequency of an number on the list
find frequency of element in list python
find the frequency of a number in a list python
count frequency of elements in python
frequency python
how to find frequency of integers in list in python
how to get frequency in python in list
find the frequency of good words in a list python
frequency in python
frequency of words in list python
find frequency of each element in list python
frequency dict python
count number frequency python
count frequency of elements in a list python
count frequency of words in string python
get frequency of elements in list python in o(1)
find the frequency of each element in a list
how to count frequency of each element in array python
python frequency count of words
find frequency of string in list of strings python
find the frequency of characters in a list in python
check frequency of word in a list
python count the frequency of a word in a text based on dictionary
how count number of frequency word in a list
python count word frequency in string
how to get frequency of each elements in a python lis
frequency of all elements in list python
counting the most frequency of words in python
python count the frequency of words in a list
calculate highest frequency elements in list python
get the frequency of the elements in a list app
count frequency of elements in many lists o(n)
wap to count the frequency of an element in a given list in python
list all items with frequency int a python list
check frequency of element list
get frequency of array elements in python
get the frequency of the elements in a list tool
highest frequency elements in list python
how to find frequency of values in python
get the frequency of the elements in a list python numpy
get the frequency of the elements in a list.
finding frequency in list in python
how to get the frequency of an element in a list python
python program to find the frequency of each element in the array using function
get frequency of elements in list and make new list
get frequency of values in list python
how to get the frequency of words in a list in python
list find frequency of a element
frequency of list elements in python
best way to find frequency of numbers in a list
frequency of a list in python
find frequency of list python
find frequency elemeent in list
python frequency of item in list
make a frequency based on a list
count frequency of word in list python
python calculate frequency of words in list
python frequency of element in list
frequency count on ordered dictonary
no of frequency counter python
check frequency of number python
count in dictionary python
count the frequency of all the list elements and store the frequency in a dictionary.
make frequency array in pythin
find freqency in python
python get frequency
freq python
find frequency in list
python frequency list count
python group list by count
python get frequency
frequency in python
count frequency of list python
get frequency list python
how to count frequency of list in python
frequency of elements in list in python
python frequency of list
how to count the frequency of a value list python
make a list for frequency and number in python
count freq in python
counting the frequency of elements inside a list using .setdefault()
count frequency of numbers in a list
list duplicate frequency in array python
store a freq file into a dict python
frequency program python
python frequency using get()
python frequency of words in list
count frequency of words in python
count frequency of word in a list of strings python
how to count frequency of words in a string python
word frequency from list python
word frequency in list python
how to check frequency using list
count frequency in array library python
count frequency of values list
word frequency counter in a list python
count frequency of words python
how to count frequency of letters in a list in python
how to count the frequency of a specific word using for loop python
python how to count the frequency of a word in a list
python program to count the frequency of each word in a sentence
count element frequency pythonb
best way to count frequency in python list
count frequency from list
frequency count in list python
frequency count list
find frequency in list python
python list count frequency
python list frequency counter
count frequency range list python
python count value frequency in list
count frequency using list comprehension python
frequency counter python
count frequency in list
python count frequency
find frequency of a number in list python

python count frequency of elements in list
count frequency in list python
how to find frequency of elements in list in python
python frequency of items in list
python list count frequency
python frequency count
how to find frequency in python
how to get frequency of words in python
python frequency list
frequency of values in list python
list frequency python
python frequency count list
how to count frequency in dictionary python
frequency of a number in a list python
python get frequency of element in list
how to find a frequency of one array in python
python group list count
python count list element frequency
how to find frequency of number in list python
get the frequency of the elements in a list python
array list frequency of object in array list
how to count the frequency of an element in array in python
count frequency of each element in an array python
frequency of object in list python
python frequency count of list
python code to count frequency of a number in a list
how to find frequncy in python
how to count number frequency in python
count frequency of all elements in list python
python program to find frequency of elements in a list
how to count the frequency of an element in a list
count frequency of number in list python
how to count item frequency in python
count frequency of each item in list
frequency of the numbers in a list
frequency of each element in a list python
frequency of each element in list python
frequency of elements in a list python
how to find frequency of elements in an array in python
write a python program to count the frequency of each element in an array.
python list element frequency
frequency of items in list python
find frequency of words in a list python
python dictionary frequency
frequency i list in python
what is frequency of element in list python
how to find frequency of a occurrence of word in python
count frequency of each value in list in python
frequency of elements of no of elements in list
frequency of each element in python list using count
frequency of a specific word in a list python
how to count the frequency of a character in python
how to check every word frequency in python
how to find frequency of a word in python
count frequency words python
how to count frequency of words in python list
count couple words frequency in a list python
python find the frequency of word
how to count frequency of each character in a list in python
word list frequency counter python dictionary
get frequency of each element in list
how to get frequency of each elements in a python lists
how to find frequency of word in a list
how to count frequency of elements in a string in python
how to count frequency of words in python nupy array
frequency of element python list
python program to get the frequency of the elements in a given list of lists
python list frequency distribution
get the frequency of each element ina list of lists in python
calculate frequency in list python
frequency of each element in python 2 different list using count
print frequency of each element in array python
check frequency of array list
frequency of number in list python
count frequency of element in list using list.count python
frequency rate of each element in an array python
find frequency of each element in array python
function to count frequency of each elemnt in a list python
frequency of a number in list python
frequency of each element in list without built in functions python
how to count the frequency in a list
python program to find the frequency of each element in the array
how to get frequency of an element in list python
how to count the frequency of an object on the list
get frequency of a value in list python
frequency of each element in an array python
frequency of element in list python till k
code to find frequency of elements in array in python
how to find the frequency in python for list
count frequency of an elements in list python
frequencyof items in list
how to get frequency of numbers in a list python
python check frequency in list
python count frequency
number of occurrences of an element in a list in python dict
count freuencies of elements in list
frequency count on ordered dictonary python
frequency of values in a list
list get frequency
frequency of occurrences python
frequency list python count
how to count which element has the max frequency in py in lists
frequency of a value in a list python
frenquency count of python list
python frequency element liste
write a python program to get the frequency of the elements in a list without using dictionary
python get frequency from list
count feqcuyency of differents list in python
python list frequency table
frequency of values python
how to get frequency in python
how to make set of unique elements from freq count in python
frequency using dictionary in python
element *frequency list python
make a list for n number and frequency in python
understanding count frequency in python
python get number of same element in list without know them
count frequency of numbersin a list
calculating frequency of all elements of list in python
python get frequnecy of values in list
how to find the the most frequency word use in a dictionaryin python
frequency of occurences in a list python
python count frequency of words in list
get frequency of a word in python
python word frequency in list
frequency of words in a list python
how to count frequency of words in list in pyhton
python list frequency
python array counter frequency
how to count frequency of words in pyhton
find the frequency of good words in a list
list the words in sentence with frequency python
frequency of a word in list python
count frequency of words in a sentence python
how to count the frequency of a word using for loop python
python how to count the frequency of a word in a listy
how do i count the frequency of a word in a sentence python
frequency list python
best way to count frequency in -python
how to use frequency in list
count frequency of values in list python
frequency number in list
python count frequency of values in list
how to check the frequency of a number in a list
how to identify frequency in a given list in python program
count frequency of element in list using list.count python without using dictionary
frequency counting python
count frequency python
how to count the frequency of an element in a list python
how to count list data frequency in python
python list get frequency
find the frequency of a number in an array in python

Count frequency of elements in a list using for loop

We can count the frequency of elements in a list using a python dictionary. To perform this operation, we will create a dictionary that will contain unique elements from the input list as keys and their count as values.

To count the frequency of elements in the list, first, we will create an empty dictionary. After that, for each new element, we will count the frequency of the element in the list. After getting the frequency of the element, we will add the element and its frequency as key-value pair to the dictionary.

We will also maintain a list of visited elements to filter out the elements that have been already visited. This can be done as follows.

myList = [1, 2, 3, 4, 1, 3, 46, 7, 2, 3, 5, 6, 10] frequencyDict = dict() visited = set() listLength = len(myList) for i in range(listLength): if myList[i] in visited: continue else: count = 0 element = myList[i] visited.add(myList[i]) for j in range(listLength - i): if myList[j+i] == element: count += 1 frequencyDict[element] = count print("Input list is:", myList) print("Frequency of elements is:") print(frequencyDict)

Output:

Input list is: [1, 2, 3, 4, 1, 3, 46, 7, 2, 3, 5, 6, 10] Frequency of elements is: {1: 2, 2: 2, 3: 3, 4: 1, 46: 1, 7: 1, 5: 1, 6: 1, 10: 1}

In the above example, we are iterating the whole list for each unique element. This makes the algorithm inefficient. In worst cases, when the list has all unique elements, we will have to process all the elements at least n*(n+1)/2 times where n is the length of the list.

To overcome this shortcoming, we will modify the above algorithm. As an improvement, we will iterate over the list only once. To count the frequency of elements, we will iterate through the list and check for each element if it is already present as a key in the dictionary or not. If the current element is already present as a key in the dictionary, we will increment the count associated with that element by 1. If the current element is not already present as a key in the dictionary, we will add a new item to the dictionary with the current element as key and 1 as its associated value.

We can implement this algorithm as follows.

myList = [1, 2, 3, 4, 1, 3, 46, 7, 2, 3, 5, 6, 10] frequencyDict = dict() visited = set() for element in myList: if element in visited: frequencyDict[element] = frequencyDict[element] + 1 else: frequencyDict[element] = 1 visited.add(element) print("Input list is:", myList) print("Frequency of elements is:") print(frequencyDict)

Output:

Input list is: [1, 2, 3, 4, 1, 3, 46, 7, 2, 3, 5, 6, 10] Frequency of elements is: {1: 2, 2: 2, 3: 3, 4: 1, 46: 1, 7: 1, 5: 1, 6: 1, 10: 1}

Improvisation to the above algorithm can be made using python try except blocks. In this method, we will use the try block to increment the frequency of the elements. Whenever an element is not already present in the dictionary, a KeyError will be raised. This will mean that the element is a unique element and its count hasn’t been added to the dictionary.

In the except block, we will catch the KeyError and add a new key-value pair to the dictionary with the current element as key and 1 as its associated value. This will be done as follows.

myList = [1, 2, 3, 4, 1, 3, 46, 7, 2, 3, 5, 6, 10] frequencyDict = dict() for element in myList: try: frequencyDict[element] = frequencyDict[element] + 1 except KeyError: frequencyDict[element] = 1 print("Input list is:", myList) print("Frequency of elements is:") print(frequencyDict)

Output:

Input list is: [1, 2, 3, 4, 1, 3, 46, 7, 2, 3, 5, 6, 10] Frequency of elements is: {1: 2, 2: 2, 3: 3, 4: 1, 46: 1, 7: 1, 5: 1, 6: 1, 10: 1}

Out of the above two algorithms, The solution which has been implemented using for loop will have almost the same efficiency for each type of input list. Whereas, the solution which uses exception handling will execute much faster for input lists having only a few elements repeated over many times in the list.