[R] princomp and prcomp confusion
Liaw, Andy
andy_liaw at merck.com
Tue Jun 27 14:35:52 CEST 2006
From: Patrick Connolly
>
> When I look through archives at
> https://stat.ethz.ch/pipermail/r-help/2003-October/040525.html
>
> I see this:
>
> Liaw, Andy wrote:
>
> >In the `Detail' section of ?princomp:
> >
> >princomp only handles so-called Q-mode PCA, that is feature
> extraction
> >of variables. If a data matrix is supplied (possibly via a
> formula) it
> >is required that there are at least as many units as variables. For
> >R-mode PCA use prcomp.
> >
>
> It doesn't appear that anyone disputed the accuracy of it.
>
>
> My current installation (version.string Version 2.3.1
> (2006-06-01)) says in the detail of princomp
>
>
> 'princomp' only handles so-called R-mode PCA, that is feature
> extraction of variables. If a data matrix is supplied (possibly
> via a formula) it is required that there are at least as many
> units as variables. For Q-mode PCA use 'prcomp'.
>
> I've not been following principal components and have only
> recently had a use for that methodology. Am I to assume that
> the later version is the correct one? I thought I'd worked
> out what the distinction between R-mode and Q-mode was, but
> now I'm as confused as ever.
>From what I can gather by googling around about R-mode and Q-mode PCA,
the current description should be the correct one.
Andy
> best
>
> --
> ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
> ~.~.~.~.~.
> ___ Patrick Connolly
> {~._.~} Great minds discuss ideas
> _( Y )_ Middle minds discuss events
> (:_~*~_:) Small minds discuss people
> (_)-(_) ..... Anon
>
> ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
> ~.~.~.~.~.
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>
>
More information about the R-help
mailing list