Related Articles

Related Articles

Python – Matrix elements Frequencies Counter
  • Last Updated : 30 Dec, 2020

Sometimes, while working with python Matrix, we can have a problem in which we need to find frequencies of all elements in Matrix. This kind of problem can have application in many domains. Lets discuss certain ways in which this task can be performed.

Method #1 : Using Counter() + sum() + map()
The combination of above methods can be used to perform this task. In this, we perform task of counting elements using Counter() and extending the logic to each row is performed using sum() and map().

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate 
# Matrix elements Frequencies Counter
# using Counter() + sum() + map()
from collections import Counter
  
# Initializing list
test_list = [[4, 5, 6], [2, 4, 5], [6, 7, 5]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# Matrix elements Frequencies Counter
# using Counter() + sum() + map()
res = dict(sum(map(Counter, test_list), Counter()))
  
# printing result 
print ("The frequencies dictionary is : " + str(res))

chevron_right


Output :

The original list is : [[4, 5, 6], [2, 4, 5], [6, 7, 5]]
The frequencies dictionary is : {2: 1, 4: 2, 5: 3, 6: 2, 7: 1}

 

Method #2 : Using chain() + Counter()
The combination of above functions can be used to perform this task. In this, we flatten the matrix using chain() and compute frequency using Counter().



filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate 
# Matrix elements Frequencies Counter
# using Counter() + chain()
from collections import Counter
import itertools
  
# Initializing list
test_list = [[4, 5, 6], [2, 4, 5], [6, 7, 5]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# Matrix elements Frequencies Counter
# using Counter() + chain()
res = dict(Counter(itertools.chain(*test_list)))
  
# printing result 
print ("The frequencies dictionary is : " + str(res))

chevron_right


Output :

The original list is : [[4, 5, 6], [2, 4, 5], [6, 7, 5]]
The frequencies dictionary is : {2: 1, 4: 2, 5: 3, 6: 2, 7: 1}

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.




My Personal Notes arrow_drop_up
Recommended Articles
Page :