TraMineR (version 1.0)

seqefsub: Searching for frequent subsequences

Description

Return a list of frequent subsequences satisfying a minimum support. Several time constraints can be set to restrict the search to specific time periods or subsequences durations.

Usage

seqefsub(seq,minSupport=NULL, pMinSupport=NULL,maxGap=-1, windowSize=-1, ageMin=-1, ageMax=-1,ageMaxEnd=-1, maxK=-1)

Arguments

seq

A list of event sequences

minSupport

The minimum support (in number of sequence)

pMinSupport

The minimum support (in percentage, will be rounded)

maxGap

The maximum time gap

windowSize

The maximum window (subsequences time

ageMin

Can be used to set a time period. If equal to -1 (default), it won't be considered.

ageMax

Can be used to set a time period. If equal to -1 (default), it won't be considered.

ageMaxEnd

Can be used to set a time period. If equal to -1 (default), it won't be considered.

maxK

The maximum number of event in a subsequence

Value

• subseq
  A list of subsequence (event sequence object) as a seqelist.
• support
  A list with the support of each subsequence in number of occurrence.

Details

The support is counted per sequence and not per occurence. The support can be set through pMinSupport as a percentage (between 0 and 1 and it will be rounded), or throught minSupport as number of sequence. It is possible to specify time constraints using maxGap, windowSize, ageMin, ageMax and ageMaxEnd. If so, two event should not be separated by more than maxGap and the whole subsequence should be included in a maximum time of windowSize. The other parameters specify the start and end age of the subsequence, it should start between ageMin and ageMax and finish before ageMaxEnd.

See Also

See seqecreate for creating event sequences. See seqeapplysub to count the number of occurence of frequent subsequences in each sequence. See is.seqelist about seqelist.

Examples

data(actcal.tse)
actcal.seqe<-seqecreate(actcal.tse$id,actcal.tse$time,actcal.tse$event)

#Searching for frequent subsequences, that is, appearing at least 20 times
fsubseq<-seqefsub(actcal.seqe,minSupport=20)
#The same using a percentage
fsubseq<-seqefsub(actcal.seqe,pMinSupport=0.01)
#Getting a string representation of subsequences
#Ten first subsequences
fsubseq$subseq[1:10]
#Support of this subsequences
fsubseq$support[1:10]


##Using time constraints
##Looking for subsequence starting in summer (between june and september)
fsubseq<-seqefsub(actcal.seqe,minSupport=10, ageMin=6, ageMax=9)
fsubseq$subseq[1:10]

##Looking for subsequence contained in summer (between june and september)
fsubseq<-seqefsub(actcal.seqe,minSupport=10, ageMin=6, ageMax=9, ageMaxEnd=9)
fsubseq$subseq[1:10]

##Looking for subsequence enclosed in a 6 month period and with a maximum gap of 2 month
fsubseq<-seqefsub(actcal.seqe,minSupport=10, maxGap=2, windowSize=6)
fsubseq$subseq[1:10]