gitinfo.py

import json
from collections import defaultdict

gitinfo = json.loads(raw_input())

files_by_user = defaultdict(set)
users_by_file = defaultdict(set)

for commit in gitinfo:
    for f in commit['files']:
        files_by_user[f].add(commit['author'])

for commit in gitinfo:
    for f in commit['files']:
        users_by_file[commit['author']].add(f)

print "File info"
print "# of commiters, filename"
print "\t[user <email>, ...]"
print "-" * 80
for f, a in files_by_user.items():
    print len(a), f
    print '\t[' + ', '.join(a) + ']'

print ""
print "Files per user"
print "# files, user <email>"
print "-" * 80
for a, f in users_by_file.items():
    print len(f), a