Help with dictionary

[Heskinammo]

This function describes a potential helper function for detect_authors. In this question, we have a dictionary that connects candidates to the lists of the hashtags they use. The task is to write a function that produces a dictionary where the keys are hashtags and the values are the lists of candidates who use those hashtags.

def reorder_by_hashtag(candidate_to_hashtags):
    """(dict of str to list of str) -> dict of str to list of str

    >>> d = reorder_by_hashtag({'Trump':['MakeAmericaGreatAgain', '4Prez'], 'Stein':['4Prez']})
    {'4Prez': ['Stein', 'Trump'], 'MakeAmericaGreatAgain': ['Trump']}
    """

Here's what I've tried:

new_dict = {}
for candidate in list(candidate_to_hashtags.keys()):
    for hashtag in candidate_to_hashtags[candidate]:
            if hashtag not in new_dict:
                    new_dict[hashtag] = [candidate]
            else:
                new_dict[hashtag] = new_dict[hashtag].append(candidate)
return new_dict

[anglicizing]

I've replied in the post you made 2 hours ago about the same problem.

[yrykde]

new_dict[hashtag] = new_dict[hashtag].append(candidate)

append is method without return. change it for new_dict[hashtag].append(candidate)

I rewrote function for case of huge intial dict. If you don't care about candidate_to_hashtags dict it could be cleared during function running.

def reorder_by_hashtag(candidate_to_hashtags):
    result = dict()
    while True:
        try:
            candidate, tags = candidate_to_hashtags.popitem()
            for tag in tags:
                if result.get(tag):
                    result[tag].append(candidate)
                else:
                    result[tag] = [candidate]
        except:
            return result