# Python | Triple List Summation

• Last Updated : 19 Feb, 2020

There can be an application requirement to append elements of 2-3 lists to one list and perform summation. This kind of application has a potential to come into the domain of Machine Learning or sometimes in web development as well. Let’s discuss certain ways in which this particular task can be performed.

Method #1 : Using + operator +` sum()`
This can be easily done using the plus operator as it does the element addition at the back of list. Similar logic is extended in case of multiple lists. The summation is performed using sum().

 `# Python3 code to demonstrate ``# Triple List Summation``# using + operator + sum()`` ` `# initializing lists``test_list1 ``=` `[``1``, ``3``, ``5``, ``5``, ``4``]``test_list2 ``=` `[``4``, ``6``, ``2``, ``8``, ``10``]``test_list3 ``=` `[``7``, ``5``, ``2``, ``9``, ``11``]`` ` `# printing original lists``print` `(``"The original list 1 is : "` `+` `str``(test_list1))``print` `(``"The original list 2 is : "` `+` `str``(test_list2))``print` `(``"The original list 3 is : "` `+` `str``(test_list3))`` ` `# using + operator + sum()``# Triple List Summation``test_list1 ``=` `sum``(test_list1 ``+` `test_list2 ``+` `test_list3)``     ` `# printing result ``print` `(``"The summed and modified list is : "` `+` `str``(test_list1))`
Output :
```The original list 1 is : [1, 3, 5, 5, 4]
The original list 2 is : [4, 6, 2, 8, 10]
The original list 3 is : [7, 5, 2, 9, 11]
The summed and modified list is : 82
```

Method #2 : Using `itertools.chain() + sum()`
The chain function can also be employed to perform this particular tasks as it uses the iterator to perform this and hence offers a better performance over the above method. The summation is performed using sum().

 `# Python3 code to demonstrate ``# Triple List Summation``# using itertools.chain() + sum()``from` `itertools ``import` `chain`` ` `# initializing lists``test_list1 ``=` `[``1``, ``3``, ``5``, ``5``, ``4``]``test_list2 ``=` `[``4``, ``6``, ``2``, ``8``, ``10``]``test_list3 ``=` `[``7``, ``5``, ``2``, ``9``, ``11``]`` ` `# printing original lists``print` `(``"The original list 1 is : "` `+` `str``(test_list1))``print` `(``"The original list 2 is : "` `+` `str``(test_list2))``print` `(``"The original list 3 is : "` `+` `str``(test_list3))`` ` `# using itertools.chain() + sum()``# Triple List Summation``test_list1 ``=` `sum``(``list``(chain(test_list1, test_list2, test_list3)))``     ` `# printing result ``print` `(``"The summed and modified list is : "` `+` `str``(test_list1))`
Output :
```The original list 1 is : [1, 3, 5, 5, 4]
The original list 2 is : [4, 6, 2, 8, 10]
The original list 3 is : [7, 5, 2, 9, 11]
The summed and modified list is : 82
```

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