Re: [R] Signs of loadings from princomp on Windows

Tony Plate Tue, 14 Sep 2004 10:12:56 -0700

FWIW, I see the same behavior as Francisco on my Windows machine (also an installation of the windows binary without trying to install any special BLAS libraries):

> library(MASS)
> data(painters)
> pca.painters <- princomp(painters[ ,1:4])
> loadings(pca.painters)

Loadings:
            Comp.1 Comp.2 Comp.3 Comp.4
Composition  0.484 -0.376  0.784 -0.101
Drawing      0.424  0.187 -0.280 -0.841
Colour      -0.381 -0.845 -0.211 -0.310
Expression   0.664 -0.330 -0.513  0.432

               Comp.1 Comp.2 Comp.3 Comp.4
SS loadings      1.00   1.00   1.00   1.00
Proportion Var   0.25   0.25   0.25   0.25
Cumulative Var   0.25   0.50   0.75   1.00
> pca.painters <- princomp(painters[ ,1:4])
> loadings(pca.painters)

Loadings:
            Comp.1 Comp.2 Comp.3 Comp.4
Composition -0.484 -0.376  0.784 -0.101
Drawing     -0.424  0.187 -0.280 -0.841
Colour       0.381 -0.845 -0.211 -0.310
Expression  -0.664 -0.330 -0.513  0.432

               Comp.1 Comp.2 Comp.3 Comp.4
SS loadings      1.00   1.00   1.00   1.00
Proportion Var   0.25   0.25   0.25   0.25
Cumulative Var   0.25   0.50   0.75   1.00
> R.version
         _
platform i386-pc-mingw32
arch     i386
os       mingw32
system   i386, mingw32
status
major    1
minor    9.1
year     2004
month    06
day      21
language R
>

My machine is a dual-processor hp xw8000.

I also get the same results with R 2.0.0 dev as in
> R.version
         _
platform i386-pc-mingw32
arch     i386
os       mingw32
system   i386, mingw32
status   Under development (unstable)
major    2
minor    0.0
year     2004
month    09
day      13
language R
>

-- Tony Plate

At Tuesday 10:25 AM 9/14/2004, Prof Brian Ripley wrote:

On Tue, 14 Sep 2004, Francisco Chamu wrote:
> I have run this on both Windows 2000 and XP.  All I did was install
> the binaries from CRAN so I think I am using the standard Rblas.dll.
>
> To reproduce what I see you must run the code at the beginning of the
> R session.
We did, as you said `start a clean session'.
I think to reproduce what you see we have to be using your account on your
computer.
> After the second run, all subsequent runs give the same > result as the second set. > > Thanks, > Francisco > > > On Tue, 14 Sep 2004 08:29:25 +0200, Uwe Ligges > <[EMAIL PROTECTED]> wrote: > > Prof Brian Ripley wrote: > > > I get the second set each time, on Windows, using the build from CRAN. > > > Which BLAS are you using? > > > > > > Works also well for me with a self compiled R-1.9.1 (both with standard > > Rblas as well as with the Rblas.dll for Athlon CPU from CRAN). > > Is this a NT-based version of Windows (NT, 2k, XP)? > > > > Uwe > > > > > > > > > > > On Tue, 14 Sep 2004, Francisco Chamu wrote: > > > > > > > > >>I start a clean session of R 1.9.1 on Windows and I run the following code: > > >> > > >> > > >>>library(MASS) > > >>>data(painters) > > >>>pca.painters <- princomp(painters[ ,1:4]) > > >>>loadings(pca.painters) > > >> > > >>Loadings: > > >> Comp.1 Comp.2 Comp.3 Comp.4 > > >>Composition 0.484 -0.376 0.784 -0.101 > > >>Drawing 0.424 0.187 -0.280 -0.841 > > >>Colour -0.381 -0.845 -0.211 -0.310 > > >>Expression 0.664 -0.330 -0.513 0.432 > > >> > > >> Comp.1 Comp.2 Comp.3 Comp.4 > > >>SS loadings 1.00 1.00 1.00 1.00 > > >>Proportion Var 0.25 0.25 0.25 0.25 > > >>Cumulative Var 0.25 0.50 0.75 1.00 > > >> > > >>However, if I rerun the same analysis, the loadings of the first > > >>component have the opposite sign (see below), why is that? I have > > >>read the note > > >>in the princomp help that says > > >> > > >> "The signs of the columns of the loadings and scores are arbitrary, > > >> and so may differ between different programs for PCA, and even > > >> between different builds of R." > > >> > > >>However, I still would expect the same signs for two runs in the same session. > > >> > > >> > > >>>pca.painters <- princomp(painters[ ,1:4]) > > >>>loadings(pca.painters) > > >> > > >>Loadings: > > >> Comp.1 Comp.2 Comp.3 Comp.4 > > >>Composition -0.484 -0.376 0.784 -0.101 > > >>Drawing -0.424 0.187 -0.280 -0.841 > > >>Colour 0.381 -0.845 -0.211 -0.310 > > >>Expression -0.664 -0.330 -0.513 0.432 > > >> > > >> Comp.1 Comp.2 Comp.3 Comp.4 > > >>SS loadings 1.00 1.00 1.00 1.00 > > >>Proportion Var 0.25 0.25 0.25 0.25 > > >>Cumulative Var 0.25 0.50 0.75 1.00 > > >> > > >>>R.version > > >> > > >> _ > > >>platform i386-pc-mingw32 > > >>arch i386 > > >>os mingw32 > > >>system i386, mingw32 > > >>status > > >>major 1 > > >>minor 9.1 > > >>year 2004 > > >>month 06 > > >>day 21 > > >>language R > > >> > > >>BTW, I have tried the same in R 1.9.1 on Debian and I can't reproduce > > >>what I see > > >>on Windows. In fact all the runs give the same as the second run on Windows. > > >> > > >>-Francisco > > >> > > >>______________________________________________ > > >>[EMAIL PROTECTED] mailing list > > >>https://stat.ethz.ch/mailman/listinfo/r-help > > >>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > >> > > >> > > > > > > > > > > > >
--
Brian D. Ripley,                  [EMAIL PROTECTED]
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
______________________________________________
[EMAIL PROTECTED] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html


______________________________________________
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PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

Re: [R] Signs of loadings from princomp on Windows

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