Inverting a dictionary with list values

Question

So, I have this index as a dict.

index = {\'Testfil2.txt\': [\'nisse\', \'hue\', \'abe\', \'pind\'], \'Testfil1.txt\': [\'hue\', \'abe\', 
\'tosse\', \'svend         


        

Answer 1

My solution for reversing a dictionary. However, it creates a new dictionary new_dic:

new_dic = {}
for k,v in index.items():
    for x in v:
        new_dic.setdefault(x,[]).append(k)

Output :

{'tosse': ['Testfil1.txt'], 'nisse': ['Testfil2.txt'], 'svend': ['Testfil1.txt'], 'abe': ['Testfil1.txt', 'Testfil2.txt'], 'pind': ['Testfil2.txt'], 'hue': ['Testfil1.txt', 'Testfil2.txt']}