From: tom soyer <tom.soyer_at_gmail.com>

Date: Thu, 3 Jan 2008 21:25:46 -0600

Date: Thu, 3 Jan 2008 21:25:46 -0600

oops, it should be: rms=(sum((x-mean(x))^2)/(length(x)-1))^(1/2)

On 1/3/08, tom soyer <tom.soyer_at_gmail.com> wrote:

*>
*

> Thanks Jim. Yes it does... but I calculated the root mean square (rms),

*> and couldn't reproduce the result without multiplying the rms by 2. I don't
**> know why...
**>
**> > x=c(2,4,3,4,5)
**> > mean(x)
**> [1] 3.6
**> > x-mean(x)
**> [1] -1.6 0.4 -0.6 0.4 1.4
**> > scale(x)
**> [,1]
**> [1,] -1.4032928
**> [2,] 0.3508232
**> [3,] -0.5262348
**> [4,] 0.3508232
**> [5,] 1.2278812
**> attr(,"scaled:center")
**> [1] 3.6
**> attr(,"scaled:scale")
**> [1] 1.140175
**> > rms=sum((x-mean(x))^2)^(1/2)/(length(x)-1)
**> > rms
**> [1] 0.5700877
**> > (x-mean(x))/rms
**> [1] -2.8065857 0.7016464 -1.0524696 0.7016464 2.4557625
**> > (x-mean(x))/(rms*2)
**> [1] -1.4032928 0.3508232 -0.5262348 0.3508232 1.2278812
**>
**>
**> On 1/3/08, jim holtman <jholtman_at_gmail.com> wrote:
**> >
**> > Does this give you what you want?
**> >
**> > > x=c(2,4,3,4,5)
**> > > ?scale
**> > > scale(x,scale=FALSE)
**> > [,1]
**> > [1,] -1.6
**> > [2,] 0.4
**> > [3,] -0.6
**> > [4,] 0.4
**> > [5,] 1.4
**> > attr(,"scaled:center")
**> > [1] 3.6
**> > >
**> >
**> > Default is to performance scaling: "If scale is TRUE then scaling is
**> > done by dividing the (centered) columns of x by their
**> > root-mean-square, and if scale is FALSE, no scaling is done. "
**> >
**> > On Jan 3, 2008 9:37 PM, tom soyer <tom.soyer_at_gmail.com> wrote:
**> > > Hi,
**> > >
**> > > The documentation for scale() states:"If center is TRUE then centering
**> > is
**> > > done by subtracting the column means (omitting NAs) of x from their
**> > > corresponding columns". But it seems that R is subtracting something
**> > else
**> > > instead of the column mean:
**> > >
**> > > > x=c(2,4,3,4,5)
**> > > > mean(x)
**> > > [1] 3.6
**> > > > x-mean(x)
**> > > [1] -1.6 0.4 -0.6 0.4 1.4
**> > > > scale(x)
**> > > [,1]
**> > > [1,] -1.4032928
**> > > [2,] 0.3508232
**> > > [3,] -0.5262348
**> > > [4,] 0.3508232
**> > > [5,] 1.2278812
**> > > attr(,"scaled:center")
**> > > [1] 3.6
**> > > attr(,"scaled:scale")
**> > > [1] 1.140175
**> > >
**> > > Notice that -1.4 is not the same as -1.6, and 1.2 is not the same as
**> > 1.4,
**> > > etc. Does anyone know what exactly is scale() doing if it is not
**> > subtracting
**> > > the column mean? Thanks.
**> > >
**> > > --
**> > > Tom
**> > >
**> > > [[alternative HTML version deleted]]
**> > >
**> > > ______________________________________________
**> > > R-help_at_r-project.org mailing list
**> > > https://stat.ethz.ch/mailman/listinfo/r-help
**> > > PLEASE do read the posting guide
**> > http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
**> > > and provide commented, minimal, self-contained, reproducible code.
**> > >
**> >
**> >
**> >
**> > --
**> > Jim Holtman
**> > Cincinnati, OH
**> > +1 513 646 9390
**> >
**> > What is the problem you are trying to solve?
**> >
**>
**>
**>
**> --
**> Tom
*

-- Tom [[alternative HTML version deleted]] ______________________________________________ R-help_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.Received on Fri 04 Jan 2008 - 03:31:09 GMT

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