subtree: Extract a subtree from a segmented PST

In PST: Probabilistic Suffix Trees and Variable Length Markov Chains

Extract a subtree from a segmented PST

Description

Extract a subtree from a segmented PST

Usage

## S4 method for signature 'PSTf'
subtree(object, group=NULL, position=NULL)

Arguments

object	A segmented probabilistic suffix tree, i.e an object of class "PSTf") as returned by the pstree, prune or tune function.
group	integer. Segment of the PST
position	Not implemented yet.

Details

See also Gabadinho 2016.

Author(s)

Alexis Gabadinho

References

Gabadinho, A. & Ritschard, G. (2016). Analyzing State Sequences with Probabilistic Suffix Trees: The PST R Package. Journal of Statistical Software, 72(3), pp. 1-39.

Examples

## activity calendar for year 2000
## from the Swiss Household Panel
## see ?actcal
data(actcal)

## selecting individuals aged 20 to 59
actcal <- actcal[actcal$age00>=20 & actcal$age00 <60,]

## defining a sequence object
actcal.lab <- c("> 37 hours", "19-36 hours", "1-18 hours", "no work")
actcal.seq <- seqdef(actcal,13:24,labels=actcal.lab)

## building a PST segmented by age group
gage10 <- cut(actcal$age00, c(20,30,40,50,60), right=FALSE,
	labels=c("20-29","30-39", "40-49", "50-59"))

actcal.pstg <- pstree(actcal.seq, nmin=2, ymin=0.001, group=gage10)

## pruning
C99 <- qchisq(0.99,4-1)/2
actcal.pstg.opt <- prune(actcal.pstg, gain="G2", C=C99)

## extracting PST for age group 20-39 and 30-39
g1.pst <- subtree(actcal.pstg.opt, group=1)
g2.pst <- subtree(actcal.pstg.opt, group=2)

## plotting the two PST
par(mfrow=c(1,2))
plot(g1.pst, withlegend=FALSE, max.level=4, main="20-29")
plot(g2.pst, withlegend=FALSE, max.level=4, main="30-39")

PST documentation built on June 22, 2024, 6:50 p.m.