# Python – Consecutive Row summation in Matrix

This particular article focuses on a problem that has utility in competitive as well as day-day programming. Sometimes, we need to get the sum between the like indices when compared with the next list. The sum between the like elements in that index is returned. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using `sum() + abs() + zip() `+ list comprehension
This particular problem can also be solved using the combination of the above 4 operations. Here zip function does the dual task of pairing the list and also pairing the like indices for sum, to be computed by abs function and then sum is found using sum function, all bounded by list comprehension.

 `# Python3 code to demonstrate ` `# Consecutive Row summation in Matrix ` `# using sum() + abs() + zip() + list comprehension ` ` `  `# initializing list  ` `test_list ``=` `[[``3``, ``4``, ``5``], [``4``, ``6``, ``8``], [``1``, ``9``, ``2``], [``3``, ``7``, ``10``]] ` ` `  `# printing original list  ` `print``(``"The original list : "` `+` `str``(test_list)) ` ` `  `# using sum() + abs() + zip() + list comprehension ` `# Consecutive Row summation in Matrix ` `res ``=` `[``sum``(``abs``(i ``+` `j) ``for` `i, j ``in` `zip``(``*``ele)) ``for` `ele ``in` `zip``(test_list, test_list[``1``:])] ` ` `  `# print result ` `print``(``"The row summation sublist : "` `+` `str``(res)) `

Output :

```The original list : [[3, 4, 5], [4, 6, 8], [1, 9, 2], [3, 7, 10]]
The row summation sublist : [30, 30, 32]
```

Method #2 : Using sum() + map() + abs + zip()
This task can also be achieved using the combination of above functions, the addition is map function that performs the task of binding of abs operation to the whole list.

 `# Python3 code to demonstrate ` `# Consecutive Row summation in Matrix ` `# using sum() + map() + abs + zip() ` ` `  `# initializing list  ` `test_list ``=` `[[``3``, ``4``, ``5``], [``4``, ``6``, ``8``], [``1``, ``9``, ``2``], [``3``, ``7``, ``10``]] ` ` `  `# printing original list  ` `print``(``"The original list : "` `+` `str``(test_list)) ` ` `  `# using sum() + map() + abs + zip() ` `# Consecutive Row summation in Matrix ` `res ``=` `[``sum``(``map``(``abs``, (i ``+` `j ``for` `i, j ``in` `zip``(x, y)))) ``for` `x, y ``in` `zip``(test_list, test_list[``1``:])] ` ` `  `# print result ` `print``(``"The row summation sublist : "` `+` `str``(res)) `

Output :

```The original list : [[3, 4, 5], [4, 6, 8], [1, 9, 2], [3, 7, 10]]
The row summation sublist : [30, 30, 32]
```

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