gistfile1.py

def snowball_search(network,twitter_api,seed_user,cur_round):
# Snowball uses create_egonet to generate new structure
    users=nodes_at_degree(network,cur_round)    # Get all the users at the current round degree
    for u in users:
        time.sleep(5)    # Wait five seconds in between to not hammer Twitter servers (H/T: @amyiris)
        search_results=create_egonet(twitter_api,u)
        network=NX.compose(network,search_results)
    return network

def create_egonet(twitter_api,seed_user):
# Function for created a directed ego-net object from inital seed Twitter user
    egonet=NX.DiGraph()
    
    # Get friend data. NOTE: we are restricted to only adding out-degree
    ego_friends=twitter_api.GetFriends(seed_user)
            
    # Create ego's edge list
    friend_ebunch=[(seed_user,str(u.screen_name)) for u in ego_friends]
    
    # Add edges
    egonet.add_edges_from(friend_ebunch)

    return egonet
    
def nodes_at_degree(network,degree):
# Get nodes to perform round k search on
    d=network.degree(with_labels=True)
    d=d.items()
    return [(a) for (a,b) in d if b==degree]