List of Dictionary – How to combine a list of dictionary Python

March 19, 2022

a =[{
    "id":"1",
    "Name":'BK',
    "Age":'56'
},
{
    "id":"1",
    "Sex":'Male'
},
{
    "id":"2",
    "Name":"AK",
    "Age":"32"
}]

I have a list of dictionary with a person information split in multiple dictionary as above for ex above id 1’s information is contained in first 2 dictionary , how can i get an output of below

{1: {'Name':'BK','Age':'56','Sex':'Male'}, 2: { 'Name': 'AK','Age':'32'}}

>Solution :

You can use some built in functions. groupby to group the dictionaries by id, then a defaultdict to collect the results.

from itertools import groupby
from collections import defaultdict

a =[{ "id":"1", "Name":'BK', "Age":'56' }, { "id":"1", "Sex":'Male' }, { "id":"2", "Name":"AK", "Age":"32" }]

results = defaultdict(dict)
key = lambda d: d['id']
for group_id, grouped in groupby(sorted(a, key=key), key=key):
    for d in grouped:
        d.pop('id')
        results[group_id].update(**d)

This gives you:

>>> results
defaultdict(<type 'dict'>, {'1': {'Age': '56', 'Name': 'BK', 'Sex': 'Male'}, '2': {'Age': '32', 'Name': 'AK'}})

The defaultdict type behaves like a normal dict, except that when you reference an unknown value, a default value is returned. This means that as the dicts in a are iterated over, the values (except for id) are updated onto either an existing dict, or an automatic newly created one.

How does collections.defaultdict work?