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Python – Mutiple Keys Grouped Summation
• Last Updated : 02 Jun, 2020

Sometimes, while working with Python records, we can have a problem in which, we need to perform elements grouping based on multiple key equality, and also summation of the grouped result of particular key. This kind of problem can occur in application in data domains. Let’s discuss certain way in which this task can be performed.

Input :
test_list = [(12, ‘M’, ‘Gfg’), (23, ‘H’, ‘Gfg’), (13, ‘M’, ‘Best’)]
grp_indx = [1, 2] [ Indices to group ]
sum_idx =  [ Index to sum ]
Output : [(‘M’, ‘Gfg’, 12), (‘H’, ‘Gfg’, 23), (‘M’, ‘Best’, 13)]

Input :
test_list = [(12, ‘M’, ‘Gfg’), (23, ‘M’, ‘Gfg’), (13, ‘M’, ‘Best’)]
grp_indx = [1, 2] [ Indices to group ]
sum_idx =  [ Index to sum ]
Output : [(‘M’, ‘Gfg’, 35), (‘M’, ‘Best’, 13)]

Method : Using loop + `defaultdict()` + list comprehension
The combination of above functionalities can be used to solve this problem. In this, we perform grouping using loop and the task of performing summation of key is done using list comprehension.

 `# Python3 code to demonstrate working of ``# Mutiple Keys Grouped Summation``# Using loop + defaultdict() + list comprehension``from` `collections ``import` `defaultdict`` ` `# initializing list``test_list ``=` `[(``12``, ``'M'``, ``'Gfg'``), (``23``, ``'H'``, ``'Gfg'``),``            ``(``13``, ``'M'``, ``'Best'``), (``18``, ``'M'``, ``'Gfg'``),``            ``(``2``, ``'H'``, ``'Gfg'``), (``23``, ``'M'``, ``'Best'``)]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing grouping indices``grp_indx ``=` `[``1``, ``2``]`` ` `# initializing sum index ``sum_idx ``=` `[``0``]`` ` `# Mutiple Keys Grouped Summation``# Using loop + defaultdict() + list comprehension``temp ``=` `defaultdict(``int``)``for` `sub ``in` `test_list:``    ``temp[(sub[grp_indx[``0``]], sub[grp_indx[``1``]])] ``+``=` `sub[sum_idx[``0``]]``res ``=` `[key ``+` `(val, ) ``for` `key, val ``in` `temp.items()]``                 ` `# printing result ``print``(``"The grouped summation : "` `+` `str``(res)) `
Output :

The original list is : [(12, ‘M’, ‘Gfg’), (23, ‘H’, ‘Gfg’), (13, ‘M’, ‘Best’), (18, ‘M’, ‘Gfg’), (2, ‘H’, ‘Gfg’), (23, ‘M’, ‘Best’)]
The grouped summation : [(‘M’, ‘Gfg’, 30), (‘H’, ‘Gfg’, 25), (‘M’, ‘Best’, 36)]

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