Table 4. The k-means clustering method and short-term periods for different datasets.

Datasets	# Days	Periods	# Clusters ( k)	Success clustering
MovieLens	210	One month	7	✓
		Two weeks	15	✓
		One week	30	✓
		One day	210
Epinions	330	One month	11	✓
		Two weeks	23	✓
		One week	47
Netflix	2190	One year	6	✓
		One season	24	✓
		One month	73	✓
		Two weeks	156