Design of a prefixspan algorithm based on prefix position form

PrefixSpan algorithm based on sequence pattern is an association without generating candidate sequences and only needs to scan the original database twice in whole operation process. Compared with other algorithms, more efficient fast. In this paper, Base Prefix Position Form, PPFPrefixSpan proposed by studying characteristics of optimizing it it. , which solves problem that produces too many duplicate projection databases process operation, optimates space/time.