python, convert a dictionary to a sorted list by value instead of key

Question

I have a collections.defaultdict(int) that I\'m building to keep count of how many times a key shows up in a set of data. I later want to be able to sort it (obviously by turnin

Answer 1

"Invert" a dictionary.

from collections import defaultdict
inv_dict = defaultdict( list )
for key, value in adict:
    inv_dict[value].append( key )
max_value= max( inv_dict.keys() )

The set of keys with the maximum occurrence --

inv_dict[max_value] 

The set of keys in descending order by occurrence --

for value, key_list in sorted( inv_dict ):
    print key_list, value