Python program to sort matrix based upon sum of rows

Given a Matrix, perform sort based upon the sum of rows.

Input : test_list = [[4, 5], [2, 5, 7], [2, 1], [4, 6, 1]] 
Output : [[2, 1], [4, 5], [4, 6, 1], [2, 5, 7]] 
Explanation : 3 < 9 < 11 < 14. Sorted sum.

Input : test_list = [[4, 5], [2, 5, 7], [4, 6, 1]] 
Output : [[4, 5], [4, 6, 1], [2, 5, 7]] 
Explanation : 9 < 11 < 14. Sorted sum. 

Method #1 : Using sort() + sum()

In this, task of sorting is done using sort(), and computation of sum is done by sum(), and passed as key fnc. to sort().

Python3

# Python3 code to demonstrate working of
# Sort Matrix by row sum
# Using sort() + sum()

# helper_fnc
def sum_sort(row):

    # getting sum
    return sum(row)

# initializing list
test_list = [[4, 5], [2, 5, 7], [2, 1], [4, 6, 1]]

# printing original list
print("The original list is : " + str(test_list))

# using sort() to perform sort
test_list.sort(key = sum_sort)

# printing result
print("Sum sorted Matrix : " + str(test_list))

Output:

The original list is : [[4, 5], [2, 5, 7], [2, 1], [4, 6, 1]] 
Sum sorted Matrix : [[2, 1], [4, 5], [4, 6, 1], [2, 5, 7]]

Method #2 : Using sorted() + sum() + lambda

In this, the task of sorting is done using sorted() and lambda is used in place of the external function call for the key.

Python3

# Python3 code to demonstrate working of
# Sort Matrix by row sum
# Using sorted() + sum() + lambda

# initializing list
test_list = [[4, 5], [2, 5, 7], [2, 1], [4, 6, 1]]

# printing original list
print("The original list is : " + str(test_list))

# using lambda function preventing fnc. call
res = sorted(test_list, key=lambda row: sum(row))

# printing result
print("Sum sorted Matrix : " + str(res))

Output:

The original list is : [[4, 5], [2, 5, 7], [2, 1], [4, 6, 1]] 
Sum sorted Matrix : [[2, 1], [4, 5], [4, 6, 1], [2, 5, 7]]