create dict with multiple values out of two lists. group multiple keys into one

Question

I have two list:

lists = ['a','b','c','d','e']
keys = [18,18,3,4,5]

what I want is a dictionary like this:

{18:['a','b'],3:'c',4:'d',5:'e'}

I keep getting this:

{18: ['a', 'b', 'c', 'd', 'e'], 3: ['a', 'b', 'c', 'd', 'e'], 4: ['a', 'b', 'c', 'd', 'e'], 5: ['a', 'b', 'c', 'd', 'e']}

I appreciate any advice!!

Answer 1

You can try this:

dicts = {key: [] for key in keys}
for k, v in zip(keys, lists):
    dicts[k].append(v)

or

from collections import defaultdict
dicts = defaultdict(list)
for k, v in zip(keys, lists):
    dicts[k].append(v)

Output:

{18: ['a', 'b'], 3: ['c'], 4: ['d'], 5: ['e']}

Answer 2

Upon reading a post suggestion from stackoverflow:

dictionary = {k: [values[i] for i in [j for j, x in enumerate(keys) if x == k]] for k in set(keys)}

I have solved it.

Answer 3

Easy way is to use zip.

dictionary = dict(zip(keys, values))

Answer 4

You can try this:

output = {}
for index, key in enumerate(keys):
    if not key in output:
        output[key] = lists[index]
    else:
        cur_val = output[key]
        if type(cur_val) == str:
            cur_val = [cur_val]
        
        cur_val.append(lists[index])        
        output[key] = cur_val
print(output)

output:

{18: ['a', 'b'], 3: 'c', 4: 'd', 5: 'e'}