def location_dict_to_lists(location_dict):
    """
    Converts a dictionary of {users : geopy location objects} to three lists
    of users, longitude, and latitude. Useful for using the zip() function.
    """
    user_list = []
    longitude_list = []
    latitude_list = []
    for user, location in location_dict.items():
        if location is not None:
            user_list.append(user)
            longitude_list.append(location.longitude)
            latitude_list.append(location.latitude)
    return user_list, longitude_list, latitude_list
