The Apriori algorithm generates candidates and tests if they are frequent. The generation of candidate itemsets and support counting are expensive in both space and time.
The FP-Growth algorithm allows frequent itemset discovery without candidate itemsets generation.
The FP growth tree is constructed by
- Scanning data and find support for each item.
- Discarding the infrequent items.
- Sorting the frequent items in decreasing order based on their support.
- Building a compact data structure called the FP-tree to map all transactions to a path in FP tree.
The height of the tree is bounded by the maximum number of items in a transaction.
FP growth is an efficient mining method of frequent patterns in large Database : using a highly compact FP‐tree, divide‐and‐conquer method in nature.