Using defaultdict to handle key not in dict

Posted on 02 Sep, 2021

We can use defauldict to eliminate the use of an if condition when looking up keys

from collections import defaultdict

users = [
    {"username": "Jenna", "language": "English"},
    {"username": "Michael", "language": "French"},
    {"username": "Gustavo", "language": "Spanish"},
    {"username": "Bhupesh", "language": "English"},
]

# normal approach
users_by_language = {}

for user in users:
    if user["language"] not in users_by_language:
        users_by_language[user["language"]] = []
    users_by_language[user["language"]].append(user)

print(users_by_language)


# defaultdict approach
users_by_language = defaultdict(list)

for user in users:
    users_by_language[user["language"]].append(user)

print(dict(users_by_language))

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