Merging two lists into dictionary while keeping duplicate data in python

Question

Hi, I want to merge two lists into one dictionary. Suppose I have two lists such as below

list_one = [\'a\', \'a\', \'c\', \'d\']

list_two = [1,2,3,4]

Answer 1

Since keys in dictionaries are unique, getting {'a': 1, 'a': 2, 'c': 3, 'd': 4} is impossible here for regular python dictionaries, since the key 'a' can only occur once. You can however have a key mapped to multiple values stored in a list, such as {'a': [1, 2], 'c': [3], 'd': [4]}.

One option is to create a defaultdict to do this easily for you:

from collections import defaultdict

list_one = ['a', 'a', 'c', 'd']

list_two = [1, 2, 3, 4]

d = defaultdict(list)
for key, value in zip(list_one, list_two):
    d[key].append(value)

print(dict(d))

Which outputs:

{'a': [1, 2], 'c': [3], 'd': [4]}