Research on Personalized Book Recommendation Based on Improved Similarity Calculation and Data Filling Collaborative Filtering Algorithm

Table 2

RMSE values of neighbor users with different numbers of clusters before and after algorithm improvement.

Number of clustered users	RMSE value of traditional collaborative filtering recommendation algorithm	RMSE value of improved collaborative filtering recommendation algorithm
5	5.903	3.469
10	5.878	4.184
15	6207	4.123
20	6.355	3.86
25	6.47	4.243
30	6.339	4.252
35	6.333	4.263
40	6.408	4.444
45	6.34	4.637
50	6.234	5