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"tree.demo" <-
function(x,y){
old.opt <- options(locatorBell = FALSE)
on.exit( options(old.opt) )
cuts <- range(x)
repeat {
cut2 <- numeric(0)
repeat {
plot(x,y,xlab=deparse(substitute(x)),
ylab=deparse(substitute(y)))
abline( v=cuts, col='blue' )
abline( v=cut2, col='red' )
cuts3 <- sort( c(cuts,cut2) )
cats <- cut( x, cuts3, include.lowest=T)
means <- tapply(y, cats, mean )
index <- tapply(y, cats )
segments(cuts3[-length(cuts3)], means, cuts3[-1], means, col='green' )
resid <- y-means[index]
ss <- round(resid %*% resid)
title( paste( "Residual sum of squares =", ss ) )
tempx <- locator(1)$x
if (length(tempx) < 1) break
cut2 <- tempx
}
if(length(cut2) < 1) break
cuts <- sort( c(cuts,cut2) )
}
}
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