[R] boot() vs S-Plus bootstrap()

[Marc Feldesman]

I'm trying to adapt some S-Plus scripts to run in R (1.2.2, Windows).  In 
one of these scripts, I've bootstrapped the prediction success rate under 
the discriminant function (lda).  The bootstrap() functions are proprietary 
to S-Plus and there aren't exact equivalents in R.  The closest is Canty's 
library boot based on the Davidson and Hinkley book.  Unfortunately, I 
haven't been able to map the commands I used in the bootstrap() function of 
S-Plus to the boot() function in the boot library of R (and also S-Plus).

Below is an example of one line from this S-Plus script.  The particular 
element I'm having trouble mapping to boot() is the
group argument.  This makes it pretty straightforward to work with 
functions that operate on multiple groups.  boot() has a strata argument, 
which *seems* like it ought to be the rough equivalent of group, but its 
operation is not entirely transparent.  Can someone point me to an example 
where boot() is used as I've illustrated below with S-Plus' bootstrap() 
function?  Unless I've missed something, there isn't an illustration in VR3 
or in the help for boot.  (There is a bivariate example, but the particular 
example doesn't translate well to something like a discriminant analysis).

Thanks for pointers.


boot.lda.success<-bootstrap(apehum, hitratio(apehum[,1], 
predict(lda(apehum[,2:11], apehum[,1]))$class)$error, group=apehum[,1], 
trace=F, B=250)







=====================
Dr. Marc R. Feldesman
Professor and Chairman
Anthropology Department
Portland State University
1721 SW Broadway
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email:  feldesmanm at pdx.edu
phone:  503-725-3081
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http://web.pdx.edu/~h1mf
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======================

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