Abstract: This paper proposed a pattern matching method based on weak-wildcards to obtain accurate and flexible matching which is good for locating critical time points and assisting users’ decision.First,a nominal sequence was obtained through coding the time series.Second,the concepts of weak-wildcard and gaps with special semantics were defined.Third,an efficient pattern matching algorithm was designed.In time series analysis,patterns reflect the trend of data change and indicate the occurrence of events.The traditional exact pattern matching is greatly affected by the noise,which has lower matching flexibility.Adding weak-wildcards gives consideration to both accuracy and flexibility.Experiments were undertaken on oil production and stock transaction data.Results show that compared to exact pattern matching method,the proposed pattern matching method copes with users’ expectation better.

Key words: Pattern matching,Time series,Weak-wildcard,Data preprocessing