It's in the Venables & Ripley MASS (ed 3) book in the section on
principal components.
The context is as follows
> ir <- rbind(iris[,,1], iris[,,2], iris[,,3])
> ir.species <- factor(c(rep("s",50),rep("c",50),rep("v",50)))
(then they use brush(ir) which I guess is not an R function)
and then
> princomp(log(ir[1:4]),cor=T)
(there is no [1:4] in the text which is probably a typo)
>From what I can see,
> iris[,,1]
is the same as
> iris
and "rbind(iris[,,1], iris[,,2], iris[,,3])" duplicates iris 3 times
while "mangling" the row index. What happens to the index and what is
the purpose of that?
I also seem to get the same result with "rbind(iris[,,1], iris[,,1],
iris[,,1])". What is the difference with "rbind(iris[,,1], iris[,,2],
iris[,,3])"?
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