find_baseline.py

#!/usr/bin/env python
from collections import defaultdict

# Convenience method 
def get_intersection(users):
    # pull out the users' following list
    list_of_follower_lists = map(lambda x: x[1], users)
    # return a list containing the common followers amongst them all
    return set(list_of_follower_lists[0]).intersection(*list_of_follower_lists)

# This is the file containing all the data fetched from Twitter
with open('twitter_ids.txt') as fo:
    ids = fo.read().splitlines()

# Convenient data structure to aggregate each person's follower set
follower_sets = defaultdict(list)
for pair in ids:
    followed, follower = pair.split(',')
    follower_sets[followed].append(follower)

# Find the 10-top most followed people
most_followers = sorted(follower_sets.iteritems(), key=lambda i: len(i[1]), reverse=True)[:10]
# Find the people that follow all 10
common_followers = get_intersection(most_followers)
# Count them
num_common_followers = len(common_followers)