# Python – Assign pair elements from Tuple Lists

• Last Updated : 30 Aug, 2020

Given a tuple list, assign with each element, its pair elements from other similar pairs.

Input : test_list = [(5, 3), (7, 5), (8, 4)]
Output : {5: [3], 7: [5], 8: [4], 4: []}
Explanation : 1st elements are paired with respective 2nd elements from all tuples.

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Input : test_list = [(5, 3)]
Output : {5: [3]}
Explanation : Only one tuples, 5 paired with 3.

Method : Using setdefault() + loop

In this, we use brute way to solve this, iterate for each tuple, and set default values for each, key and value as empty list, appending the elements to respective list if already present.

## Python3

 `# Python3 code to demonstrate working of ``# Assign pair elements from Tuple Lists``# Using setdefault + loop`` ` `# initializing list``test_list ``=` `[(``5``, ``3``), (``7``, ``5``), (``2``, ``7``), (``3``, ``8``), (``8``, ``4``)]`` ` `# printing string``print``(``"The original list : "` `+` `str``(test_list))`` ` `# initializing dictionary``res ``=` `dict``()``for` `key, val ``in` `test_list:``     ` `    ``# adding to both, corresponding keys and values``    ``res.setdefault(val, [])``    ``res.setdefault(key, []).append(val)`` ` `# printing results ``print``(``"The resultant pairings : "` `+` `str``(res))`
Output
```The original list : [(5, 3), (7, 5), (2, 7), (3, 8), (8, 4)]
The resultant pairings : {3: [8], 5: [3], 7: [5], 2: [7], 8: [4], 4: []}
```
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