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Python – Rows with K string in Matrix
  • Last Updated : 11 Oct, 2020

Given a matrix, extract row numbers with particular string occurrence.

Input : test_list = [[“GFG”, “best”, “geeks”], [“geeks”, “rock”], [“GFG”, “for”, “CS”], [“Keep”, “learning”]], K = “GFG” 
Output : [0, 2] 
Explanation : 0th index and 2nd index have “GFG” in them as element.

Input : test_list = [[“GFG”, “best”, “geeks”], [“geeks”, “rock”, “GFG”], [“GFG”, “for”, “CS”], [“Keep”, “learning”]], K = “GFG” 
Output : [0, 1, 2] 
Explanation : 0th index, 1st index and 2nd index have “GFG” in them as element. 

Method #1 : Using loop

In this, we iterate for each element in Matrix and get the indices of all the rows which match the K string.



Python3




# Python3 code to demonstrate working of
# Rows with K string in Matrix
# Using loop
  
# initializing list
test_list = [["GFG", "best", "geeks"], ["geeks", "rock"],
             ["GFG", "for", "CS"], ["Keep", "learning"]]
  
# printing original list
print("The original list is : ", test_list)
  
# initializing K
K = "GFG"
  
res = []
  
# enumerate() used for getting both index and ele
for idx, ele in enumerate(test_list):
  
    # checking for K String
    if K in ele:
        res.append(idx)
  
# printing result
print("Rows with K : " + str(res))

Output:

The original list is :  [[‘GFG’, ‘best’, ‘geeks’], [‘geeks’, ‘rock’], [‘GFG’, ‘for’, ‘CS’], [‘Keep’, ‘learning’]]
Rows with K : [0, 2]

Method #2 : Using list comprehension

This is similar to above method, difference being its a shorthand to solve problem.

Python3




# Python3 code to demonstrate working of
# Rows with K string in Matrix
# Using list comprehension
  
# initializing list
test_list = [["GFG", "best", "geeks"], ["geeks", "rock"],
             ["GFG", "for", "CS"], ["Keep", "learning"]]
  
# printing original list
print("The original list is : ", test_list)
  
# initializing K
K = "GFG"
  
# shorthand to get result
res = [idx for idx, ele in enumerate(test_list) if K in ele]
  
# printing result
print("Rows with K : " + str(res))

Output:

The original list is :  [[‘GFG’, ‘best’, ‘geeks’], [‘geeks’, ‘rock’], [‘GFG’, ‘for’, ‘CS’], [‘Keep’, ‘learning’]]
Rows with K : [0, 2]

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