PST (version 0.94.1)

subtree: Extract a subtree from a segmented PST

Description

Extract a subtree from a segmented PST

Usage

# S4 method for 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.

Author

Alexis Gabadinho

Details

See also Gabadinho 2016.

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")