Python - Concatenate string rows in Matrix

Python – Concatenate string rows in Matrix

Last Updated : 30 Dec, 2020

The problems concerning matrix are quite common in both competitive programming and Data Science domain. One such problem that we might face is of finding the concatenation of rows of matrix in uneven sized matrix. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using join() + list comprehension
The combination of above functions can help to get the solution to this particular problem in just a one line and hence quite useful. The join function computes the concatenation of sublists and all this bound together using list comprehension.

# Python3 code to demonstrate
# Row String Concatenation Matrix
# using join() + list comprehension
  
# initializing list
test_list = [['gfg', ' is', ' best'], ['Computer', ' Science'], ['GeeksforGeeks']]
  
# printing original list
print("The original list : " + str(test_list))
  
# using join() + list comprehension
# Row String Concatenation Matrix
res = [''.join(idx for idx in sub) for sub in test_list ]
  
# print result
print("The row concatenation in matrix : " + str(res))

Output :

The original list : [['gfg', ' is', ' best'], ['Computer', ' Science'], ['GeeksforGeeks']]
The row concatenation in matrix : ['gfg is best', 'Computer Science', 'GeeksforGeeks']

Method #2 : Using loop
This task can also be performed in brute force manner in which we just iterate the sublists and perform join in brute manner creating new string for each sublist and appending in list.

# Python3 code to demonstrate
# Row String Concatenation Matrix
# using loop
  
# initializing list
test_list = [['gfg', ' is', ' best'], ['Computer', ' Science'], ['GeeksforGeeks']]
  
# printing original list
print("The original list : " + str(test_list))
  
# using loop
# Row String Concatenation Matrix
res = []
for sub in test_list:
    res_sub = ""
    for idx in sub:
        res_sub = res_sub + idx
    res.append(res_sub)
  
# print result
print("The row concatenation in matrix : " + str(res))

Output :

The original list : [['gfg', ' is', ' best'], ['Computer', ' Science'], ['GeeksforGeeks']]
The row concatenation in matrix : ['gfg is best', 'Computer Science', 'GeeksforGeeks']

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