[R] standardising a data matrix

[ben@zoo.ufl.edu]

On Fri, 2 Mar 2001, Tord Snall wrote:

> Dear all,
> I would like to standardise my data. Here is an exemple for two columns:
>
> > onorm<- read.table("onorm.txt", header=T)
> > names(onorm)
> [1] "on1" "on2" "on3" "on4" "on5"
> > norm<- data.frame((onorm$on1-mean(onorm$on1))/stdev(onorm$on1),
> (onorm$on2-mean(onorm$on2))/stdev(onorm$on2))
>
> I would be happy however not having got to do this coulumnwise since I have
> about 80 columns. Could someone please give a hint on how to do this for
> the whole matrix.

  Hints (someone else will probably come along and give you the whole
answer):  see "sweep", "scale", "apply".

  For the names,
  names(newdata) <- paste("s",names(olddata),sep="")


>
> The names of the coulumns are on1, on2 etc. as above. I want the columns in
> the new standardised dataset to have the names son1, son2 etc, i.e. adding
> an s to all the original column names. How do I do that?
>
> Thanks in advance!
>
> Sincerely,
> Tord Snäll
>
> -----------------------------------------------------------------------
> Tord Snäll
> Avd. f växtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
> Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
> Villavägen 14
> SE-752 36 Uppsala, Sweden
> Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
> Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
> Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
> E-mail: Tord.Snall at ebc.uu.se
> http://www.vaxtbio.uu.se/resfold/tord_s.htm
> ------------------------------------------------------------------------
>
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