Replace values with lists in python

Question

I've created a dictionary of employees and past companies:

{person 1: [company 2, company 3], person 2: [company 2]}

Now, I want to replace each company in each list with a list of people who have worked in that company.

I would like the final result to be an adjacency list (i.e. a dictionary with persons as both the key and values.

Answer 1

You'll need to loop through your map and create another map of company: people, then use that map to generate the third map of people: people

pc_map = # your person: company map
cp_map = {}
for person, companies in pc_map.items():
    for company in companies:
        cp_map.setdefault(company, []).append(person)

pp_map = {}
for person, companies in pc_map.items():
    pp_map[person] = [cp_map[company] for company in companies]