Python asside function returns none

Question

I have the orders of a platform in a csv file and I want to organize it to put in a database (probably mongodb). So the final data structure may be:

{'user1':
    {'meals': {'hamburger': 2}, {'pizza': 1},
    {'weekdays': {'monday': 1}},{'tuesday':1}, {'friday': 1}
}

So, I am trying to do a very simple code that organize the number of ocurrencies, but before I want to structure the dictionary keys dinamically. The data is in a csv file

import csv
import pprint


def addKeysNestedDict(dictionary, keys):
    # print(dictionary)
    if len(keys) > 1:
        if keys[0] not in dictionary.keys():
            dictionary[keys[0]] = {'meals': '', 'weekdays': ''}
            print('inside addKeys IF: ')
            print(dictionary)
        addKeysNestedDict(dictionary, keys[1:])
    else:
        dictionary[keys[0]] = {'meals': '', 'weekdays': ''}
        print('inside addKeys: ')
        print(dictionary) # PRINTS EXPECTED VALUES
        return dictionary


def organize_orders(file):
    pp = pprint.PrettyPrinter(indent=4)
    dict_read = csv.DictReader(file, fieldnames=['name', 'food', 'day'])
    list_dict = list(dict_read)
    set_names = set()
    set_food = set()
    set_day = set()
    # people = {} # DOESN'T MATTER IF IT IS DECLARED BOFORE
    for n in list_dict:
        set_names.add(n['name'])
        set_food.add(n['food'])
        set_day.add(n['day'])
    print(addKeysNestedDict({}, list(set_names))) # PRINTS NONE
    people = (addKeysNestedDict({}, list(set_names)))
    print('people: ')
    print(people) # PRINTS NONE
    # for s_n in set_names:
    #     for s_f in set_food:
            # for s_d in set_day:
            #     people[s_n][s_f] = list_dict.count(s_f)
            #     people[s_n][s_d] = list_dict.count(s_d)

def analyze_log(path_to_file):
    with open(path_to_file) as csvfile:
        return(organize_orders(csvfile))


analyze_log('some csv file with path')

I culd not figure out why I get none returned from addKeysNestedDict() method, since it prints exactly what I want one line before method return

You have a whole branch of that function that doesn't return anything, and thus returns None implicitly. — Kemp, Aug 24 '21 at 16:00

Captain Trojan · Answer 1 · 2021-08-24T16:05:25.290

0

Change the function to:

def addKeysNestedDict(dictionary, keys):
    # print(dictionary)
    if len(keys) > 1:
        if keys[0] not in dictionary.keys():
            dictionary[keys[0]] = {'meals': '', 'weekdays': ''}
            print('inside addKeys IF: ')
            print(dictionary)
        addKeysNestedDict(dictionary, keys[1:])
    else:
        dictionary[keys[0]] = {'meals': '', 'weekdays': ''}
        print('inside addKeys: ')
        print(dictionary) # PRINTS EXPECTED VALUES
    return dictionary

Notice that I moved the return dictionary statement out of the specific branch, which causes both of your branches to return the dictionary you're building in your function.

edited Aug 24 '21 at 16:05

answered Aug 24 '21 at 16:01

Captain Trojan

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It's generally considered better to explain what change you've made and why rather than just give the code. If nothing else, it'll let people know there's not another change in there that's harder to spot than the obvious one. – Kemp Aug 24 '21 at 16:03
@Kemp I rather help people than just vote close for typo/unrepeatability, but you're right. – Captain Trojan Aug 24 '21 at 16:04
me: ‍♂️ thank you Captain! – batista Aug 24 '21 at 16:17

Python asside function returns none

1 Answers1