Structure inserted dict

tools.py

import datetime
import random
import json


def get_rand_dates_list(amount):
    return [
        datetime.datetime(random.randint(2010, 2016), random.randint(1, 12), 1)
        for i in range(amount)]


def structure_dates(dates_list):
    result = {}
    for date in dates_list:
        year = result.setdefault(date.year, {})
        month = year.setdefault(date.month, [])
        month.append(str(date))
    result = [[k, list(v.items())] for k, v in result.items()]
    return result

if __name__ == '__main__':
    structured_dates = structure_dates(get_rand_dates_list(12))
    print(json.dumps({'data': structured_dates}, indent=4))