[R] What does "rbind(iris[,,1], iris[,,2], iris[,,3])" do?

Prof Brian Ripley ripley at stats.ox.ac.uk
Thu Apr 13 10:24:36 CEST 2006

'iris' in S-PLUS is not the same as 'iris' in R, rather similar to 'iris3' 
in R.

You need the fourth (2002) edition of the book to work with R.

The book does say in many places (including its title) it is about 
'S-PLUS', but does have on-line complements about the changes needed for R 
of a similar vintage (last updated Dec 2001).

You are trying to use a book written in 1998 on a different system in 
2006, and you have the audacity to accuse the authors of making errors
because it does not work.  I look forwards to receiving your apology.

On Thu, 13 Apr 2006, Sasha Pustota wrote:

> 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)

No, just your error.

>> 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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Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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