[R] question about scale() function
jim holtman
jholtman at gmail.com
Fri Jan 4 03:46:21 CET 2008
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]]
>
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>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
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