# Python – Order Tuples by List

Sometimes, while working with Python tuples, we can have a problem in which we need to perform ordering of all the tuples keys using external list. This problem can have application in data domains such as Data Science. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [(‘Gfg’, 10), (‘best’, 3), (‘CS’, 8), (‘Geeks’, 7)], ord_list = [‘Geeks’, ‘best’, ‘CS’, ‘Gfg’]
Output : [(‘Geeks’, 7), (‘best’, 3), (‘CS’, 8), (‘Gfg’, 10)]

Input : test_list = [(‘best’, 3), (‘CS’, 8), (‘Geeks’, 7)], ord_list = [‘Geeks’, ‘best’, ‘CS’]
Output : [(‘Geeks’, 7), (‘best’, 3), (‘CS’, 8)]

Method #1 : Using `dict()` + list comprehension
The combination of above functions can be used to solve this problem. In this, we perform this task by converting tuple list to dictionaries, and as a second step use list comprehension to iterate through list and map the dictionary keys with values.

 `# Python3 code to demonstrate working of  ` `# Order Tuples by List ` `# Using dict() + list comprehension ` ` `  `# initializing list ` `test_list ``=` `[(``'Gfg'``, ``3``), (``'best'``, ``9``), (``'CS'``, ``10``), (``'Geeks'``, ``2``)] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initializing order list  ` `ord_list ``=` `[``'Geeks'``, ``'best'``, ``'CS'``, ``'Gfg'``] ` ` `  `# Order Tuples by List ` `# Using dict() + list comprehension ` `temp ``=` `dict``(test_list) ` `res ``=` `[(key, temp[key]) ``for` `key ``in` `ord_list] ` ` `  `# printing result  ` `print``(``"The ordered tuple list : "` `+` `str``(res))  `

Output :

```The original list is : [('Gfg', 3), ('best', 9), ('CS', 10), ('Geeks', 2)]
The ordered tuple list : [('Geeks', 2), ('best', 9), ('CS', 10), ('Gfg', 3)]
```

Method #2 : Using `setdefault() + sorted() `+ lambda
The combination of above functions can be used to solve this problem. In this, we perform task of mapping elements to indices and creating a lookup using setdefault. And, as a second step, using sorted to sort list using lookup dictionary value list.

 `# Python3 code to demonstrate working of  ` `# Order Tuples by List ` `# Using setdefault() + sorted() + lambda ` ` `  `# initializing list ` `test_list ``=` `[(``'Gfg'``, ``3``), (``'best'``, ``9``), (``'CS'``, ``10``), (``'Geeks'``, ``2``)] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initializing order list  ` `ord_list ``=` `[``'Geeks'``, ``'best'``, ``'CS'``, ``'Gfg'``] ` ` `  `# Order Tuples by List ` `# Using setdefault() + sorted() + lambda ` `temp ``=` `dict``() ` `for` `key, ele ``in` `enumerate``(ord_list): ` `    ``temp.setdefault(ele, []).append(key)        ` `res ``=` `sorted``(test_list, key ``=` `lambda` `ele: temp[ele[``0``]].pop())   ` ` `  `# printing result  ` `print``(``"The ordered tuple list : "` `+` `str``(res))  `

Output :

```The original list is : [('Gfg', 3), ('best', 9), ('CS', 10), ('Geeks', 2)]
The ordered tuple list : [('Geeks', 2), ('best', 9), ('CS', 10), ('Gfg', 3)]
```

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.