Function that makes dict from string but swaps keys and values?-CodePudding

I'm trying to make a function that takes in list of strings as an input like the one listed below:

def swap_values_dict(['Summons: Bahamut, Shiva, Chocomog',
 'Enemies: Bahamut, Shiva, Cactaur'])

and creates a dictionary from them using the words after the colons as keys and the words before the colons as values. I need to clarify that, at this point, there are only two strings in the list. I plan to split the strings into sublists and, from there, try and assign them to a dictionary.

The output should look like

{'Bahamut': ['Summons','Enemies'],'Shiva':['Summons','Enemies'],'Chocomog':['Summons'],'Cactaur':['Enemies']}

As you can see, the words after the colon in the original list have become keys while the words before the colon (categories) have become the values. If one of the values appears in both lists, it is assigned two values in the final dictionary. I would like to be able to make similar dictionaries out of many lists of different sizes, not just ones that contain two strings. Could this be done without list comprehension and only for loops and if statements?

What I've Tried So Far

title_list = []
for i in range(len(mobs)):#counts amount of strings in list
    titles = (mobs[i].split(":"))[0] #gets titles from list using split
    title_list.append(titles)
title_list

this code returns ['Summons', 'Enemies'] which aren't the results I wanted to receive but I think they could help me write the function. I had planned on separating the keys and values into separate lists and then zipping them together afterwards as a dictionary.

CodePudding user response：

You could first split on ': ' to separate the keys and values; then split on ', ' to separate the items in the values:

def swap_values_dict(lst):
    out = {}
    for x in lst:
        k,v = x.split(': ')
        out[k] = v.split(', ')
    return out

res = swap_values_dict(['Summons: Bahamut, Shiva, Chocomog', 'Enemies: Bahamut, Shiva, Cactaur'])

Output:

{'Summons': ['Bahamut', 'Shiva', 'Chocomog'],
 'Enemies': ['Bahamut', 'Shiva', 'Cactaur']}

CodePudding user response：

Try:

def swap_values_dict(lst):
    tmp = {}
    for s in lst:
        k, v = map(str.strip, s.split(":"))
        tmp[k] = list(map(str.strip, v.split(",")))

    out = {}
    for k, v in tmp.items():
        for i in v:
            out.setdefault(i, []).append(k)

    return out


print(
    swap_values_dict(
        [
            "Summons: Bahamut, Shiva, Chocomog",
            "Enemies: Bahamut, Shiva, Cactaur",
        ]
    )
)

Prints:

{
    "Bahamut": ["Summons", "Enemies"],
    "Shiva": ["Summons", "Enemies"],
    "Chocomog": ["Summons"],
    "Cactaur": ["Enemies"],
}

CodePudding user response：

I'd use a defaultdict. It saves you the trouble of manually checking if a key exists in your dictionary and constructing a new empty list, making for a rather concise function:

from collections import defaultdict

def swap_values_dict(mobs):
    result = defaultdict(list)
    
    for elem in mobs:
        role, members = elem.split(': ')
        for m in members.split(', '):
            result[m].append(role)

    return result