surprise_predict.py

testSet = trainingSet.build_anti_testset()
predictions = knn.test(testSet)

from collections import defaultdict
 
def get_top3_recommendations(predictions, topN = 3):
     
    top_recs = defaultdict(list)
    for uid, iid, true_r, est, _ in predictions:
        top_recs[uid].append((iid, est))
     
    for uid, user_ratings in top_recs.items():
        user_ratings.sort(key = lambda x: x[1], reverse = True)
        top_recs[uid] = user_ratings[:topN]
     
    return top_recs