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from surprise import KNNBaseline
from surprise import Dataset
from surprise import Reader
import time
import threading
import sys
import json
def synchronized(func):
func.__lock__ = threading.Lock()
def synced_func(*args, **kws):
with func.__lock__:
return func(*args, **kws)
return synced_func
def train(filename):
"""Returns algo object. Input file is a CSV of user_id, item_id, rating."""
reader = Reader(line_format='user item rating', sep=',', rating_scale=[-1,1])
data = Dataset.load_from_file(filename, reader=reader)
trainset = data.build_full_trainset()
algo = KNNBaseline(sim_options={'user_based': False})
algo.fit(trainset)
return algo
@synchronized
def set_rating(algo, user_id, item_id, rating):
"""Should work even if user_id is new. Nice if it works with new item_ids too.
If rating is None, it means unset the rating.
You just need to update anything needed by the top function."""
# need to update:
# algo.yr
# algo.bu
# algo.by
# algo._raw2inner_id_users
# optional:
# trainset.to_inner_iid
# trainset.knows_item
# algo.bi
# algo.bx
# algo.sim
# algo.ir
# algo._raw2inner_id_items
if not algo.trainset.knows_item(item_id):
return
inner_item_id = algo.trainset.to_inner_iid(item_id)
try:
inner_user_id = algo.trainset.to_inner_uid(user_id)
new_user = False
except ValueError:
inner_user_id = len(algo.trainset._raw2inner_id_users)
new_user = True
new_bu = np.append(algo.bu, 0)
algo.bu = new_bu
algo.by = new_bu
algo.yr[inner_user_id] = []
new_ratings = [(i, r) for i, r in algo.yr[inner_user_id] if i != inner_item_id]
if rating is not None:
new_ratings += [(inner_item_id, rating)]
algo.yr[inner_user_id] = new_ratings
if new_user:
# Do this last to make sure score doesn't get messed up if it calls while
# this function is executing (a likely occurrence).
algo.trainset._raw2inner_id_users[user_id] = inner_user_id
def normalize_pred(pred):
ret = {'score': pred.est,
'item-id': pred.iid}
if 'actual_k' in pred.details:
ret['knn/k'] = pred.details['actual_k']
else:
ret['knn/k'] = 0
return ret
def top(algo, user_id, item_ids, verbose=False):
"""Returns a list of dicts corresponding to item_ids. Contains a "score" key
and any other keys that should be recorded along with the recommendation."""
start = time.monotonic()
ret = sorted([normalize_pred(algo.predict(user_id, item_id, clip=False))
for item_id in item_ids],
key=lambda x: (x['score'], x['knn/k']),
reverse=True)[:20]
if verbose:
print("top:", time.monotonic() - start)
return ret
def main(ratings_file, user_candidates_file):
algo = train(ratings_file)
with open(user_candidates_file, 'r') as f:
user_id, item_ids = json.loads(f.read())
score(algo, user_id, item_ids, verbose=True)
if __name__ == "__main__":
main(*sys.argv[1:])
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