# Python | Selective Merge list every Nth position

Sometimes, while working with Python list, we can come into a problem in which we need to perform merging in list. A simple merge of list is easier to perform. But sometimes, we need to handle variations in merge. One such can be merge one list with other at every Nth element. This particular problem can be faced in day-day programming and competitive programming. Let’s discuss certain way in which this task can be performed.

Method : Using loop + `extend() + iter() + next()`
In this method, we use a brute force approach to tackle this problem. In this we convert a larger list into an iterator and then access it’s element using next(). The whole idea behind this is faster access of elements. Smaller list is checked for every N element.

 `# Python3 code to demonstrate working of ` `# Selective Merge list every Nth position ` `# using loop + extend() + iter() + next() ` ` `  `# initialize lists ` `test_list1 ``=` `[``1``, ``4``, ``9``, ``10``, ``19``, ``65``, ``78``, ``23``, ``78``] ` `test_list2 ``=` `[``8``, ``14``, ``50``] ` ` `  `# printing original lists ` `print``(``"The original list 1 is : "` `+` `str``(test_list1)) ` `print``(``"The original list 2 is : "` `+` `str``(test_list2)) ` ` `  `# Selective Merge list every Nth position ` `# using loop + extend() + iter() + next() ` `N ``=` `3` `temp_iter ``=` `iter``(test_list1) ` `res ``=` `[] ` `for` `ele ``in` `test_list2: ` `    ``res.extend([``next``(temp_iter) ``for` `_ ``in` `range``(N ``-` `1``)]) ` `    ``res.append(ele) ` `res.extend(temp_iter) ` ` `  `# printing result ` `print``(``"The List after merge is : "` `+` `str``(res)) `

Output :

```The original list 1 is : [1, 4, 9, 10, 19, 65, 78, 23, 78]
The original list 2 is : [8, 14, 50]
The List after merge is : [1, 4, 8, 9, 10, 14, 19, 65, 50, 78, 23, 78]
```

My Personal Notes arrow_drop_up Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Article Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.