Re: [R] plotting other axes for PCA

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Fri, 18 Jan 2008 17:35:41 +0000 (GMT)

On Fri, 18 Jan 2008, Silvia Lomascolo wrote:

>
> Hi R-community,
> I am doing a PCA and I need plots for different combinations of axes (e.g.,
> PC1 vs PC3, and PC2 vs PC3) with the arrows indicating the loadings of each
> variables. What I need is exactly what I get using biplot (pca.object) but
> for other axes.

The prcomp and princomp methods of biplot() have argument 'choices' that does exactly what you seem to be asking for.

> I have plotted PC2 and 3 using the scores of the cases, but I don't get the
> arrows proportional to the loadings of each variables on each axis.
>
> Any hints on this?
>
> Thanks, Silvia.

-- 
Brian D. Ripley,                  ripley_at_stats.ox.ac.uk
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

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Received on Fri 18 Jan 2008 - 17:56:14 GMT

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