tom soyer wrote: > oops, it should be: rms=(sum((x-mean(x))^2)/(length(x)-1))^(1/2) > sd(x) does the same thing.
domenico > On 1/3/08, tom soyer <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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@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 >> > > > > > ______________________________________________ R-help@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.
