How to Count Supports of Candidates? Why counting supports of candidates a problem? The total number of candidates can be very huge One transaction may contain many candidates Method Candidate itemsets are stored in a hash-tree Leaf node of hash-tree contains a list of itemsets and counts Interior node contains a hash table Subset function: finds all the candidates contained in a transaction February 4, 2021 Data Mining: Concepts and Techniques 16February 4, 2021 Data Mining: Concepts and Techniques 16 How to Count Supports of Candidates? ◼ Why counting supports of candidates a problem? ◼ The total number of candidates can be very huge ◼ One transaction may contain many candidates ◼ Method: ◼ Candidate itemsets are stored in a hash-tree ◼ Leaf node of hash-tree contains a list of itemsets and counts ◼ Interior node contains a hash table ◼ Subset function: finds all the candidates contained in a transaction