[R] Function to convert categorical variable in numerical

[Prof Brian Ripley]

?model.matrix
?contr.treatment

Whether this makes sense for PCA is another matter: princomp() contains a 
test to stop this happening automatically with a formula argument. One 
problem is the result depends on just how you do the transformation.


On Thu, 24 May 2007, J.Andrés Martínez wrote:

> Hello everybody,
>
> I am a new R user. At current moment I need to do a Principal Components
> Analysis with a table who contain mixed variables (categorical and
> numerical). There is some function available in R for transform these
> variables?
>
> For example: I need transform the categorical variable X who has 3 classes
> in 2 numerical variables with 0s and 1s.
>
> Thank you very much,
> J. Andres
>
> 	[[alternative HTML version deleted]]
>
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-- 
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