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Python – Matrix Row subset

  • Last Updated : 30 Dec, 2020
Geek Week

Sometimes, while working with Python Matrix, one can have a problem in which, one needs to extract all the rows that are a possible subset of any row of other Matrix. This kind of problem can have application in data domains as a matrix is a key data type in those domains. Let’s discuss certain ways in which this problem can be solved.

Input : test_list = [[4, 5, 7], [2, 3, 4], [9, 8, 6]], check_matr = [[2, 3], [1, 2], [9, 0]]
Output : [[2, 3]]

Input : test_list = [[4, 1, 2], [2, 3, 4], [9, 8, 0]], check_matr = [[2, 3], [1, 2], [9, 0]]
Output : [[2, 3], [1, 2], [9, 0]]

Method #1 : Using any() + all() + list comprehension
The combination of above functions offer a way in which this problem can be solved. In this, we check for occurrence of all elements of row using all() and any() is used to match to any row of Matrix. List comprehension is used to bind the logic together.




# Python3 code to demonstrate working of 
# Matrix Row subset
# Using any() + all() + list comprehension
  
# initializing lists
test_list = [[4, 5, 7], [2, 3, 4], [9, 8, 0]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing check Matrix
check_matr = [[2, 3], [1, 2], [9, 0]]
  
# Matrix Row subset
# Using any() + all() + list comprehension
res = [ele for ele in check_matr if any(all(a in sub for a in ele)
                                           for sub in test_list)]
  
# printing result 
print("Matrix row subsets : " + str(res)) 
Output :



The original list is : [[4, 5, 7], [2, 3, 4], [9, 8, 0]]
Matrix row subsets : [[2, 3], [9, 0]]

 

Method #2 : Using product() + set() + list comprehension
The combination of above functions can be used for this task. In this, we perform the task of nested loop using product() and set() conversion is to check for subset of one container over other. List comprehension is used to bind all together.




# Python3 code to demonstrate working of 
# Matrix Row subset
# Using product() + set() + list comprehension
import itertools
  
# initializing lists
test_list = [[4, 5, 7], [2, 3, 4], [9, 8, 0]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing check Matrix
check_matr = [[2, 3], [1, 2], [9, 0]]
  
# Matrix Row subset
# Using product() + set() + list comprehension
res = [a for a, b in itertools.product(check_matr, test_list)
                                         if set(a) <= set(b)]
  
# printing result 
print("Matrix row subsets : " + str(res)) 
Output :
The original list is : [[4, 5, 7], [2, 3, 4], [9, 8, 0]]
Matrix row subsets : [[2, 3], [9, 0]]

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