Python - List Strings frequency in Matrix

Python – List Strings frequency in Matrix

Last Updated : 09 Mar, 2020

Sometimes, while working with Matrix, we can have a problem in which we need to check frequency of argument Strings from List in each row of Matrix. This is very peculiar problem and can have usefulness in many domains. Lets discuss certain ways in which this task can be solved.

Method #1 : Using count() + loop
The combination of above functionalities can be used to perform this task. In this we count the frequency using count() and task of iteration is performed inside the loop.

# Python3 code to demonstrate 
# List Strings frequency in Matrix
# using count() + loop
  
# Initializing lists
test_list1 = [['Gfg', 'is', 'best'], ['Gfg', 'is', 'for', 'CS'], ['Gfg', 'is', 'for', 'Geeks']]
test_list2 = ['Gfg', 'is', 'best']
  
# printing original list1
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
  
# List Strings frequency in Matrix
# using count() + loop
res = []
for val in test_list1:
    res.append([val.count(ele) for ele in test_list2])
  
# printing result 
print ("Frequency of strings in Matrix : " + str(res))

Output :

The original list 1 is : [['Gfg', 'is', 'best'], ['Gfg', 'is', 'for', 'CS'], ['Gfg', 'is', 'for', 'Geeks']]
The original list 2 is : ['Gfg', 'is', 'best']
Frequency of strings in Matrix : [[1, 1, 1], [1, 1, 0], [1, 1, 0]]

Method #2 : Using list comprehension
This is yet another way in which this task can be performed. This is shortened version of above method in one liner.

# Python3 code to demonstrate 
# List Strings frequency in Matrix
# using list comprehension
  
# Initializing lists
test_list1 = [['Gfg', 'is', 'best'], ['Gfg', 'is', 'for', 'CS'], ['Gfg', 'is', 'for', 'Geeks']]
test_list2 = ['Gfg', 'is', 'best']
  
# printing original list1
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
  
# List Strings frequency in Matrix
# using list comprehension
res = [[sub.count(ele) for ele in test_list2] for sub in test_list1]
  
# printing result 
print ("Frequency of strings in Matrix : " + str(res))

Output :

The original list 1 is : [['Gfg', 'is', 'best'], ['Gfg', 'is', 'for', 'CS'], ['Gfg', 'is', 'for', 'Geeks']]
The original list 2 is : ['Gfg', 'is', 'best']
Frequency of strings in Matrix : [[1, 1, 1], [1, 1, 0], [1, 1, 0]]

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