[R] convert factor dataframe into numeric matrix

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 24.10.2007 16:24:29:

> 
> ----- Original Message ----- 
> From: "Prof Brian Ripley" <ripley at stats.ox.ac.uk>
> To: "sun" <flyhyena at yahoo.com.cn>
> Cc: <r-help at stat.math.ethz.ch>
> Sent: Wednesday, October 24, 2007 2:58 PM
> Subject: Re: [R] convert factor dataframe into numeric matrix
> 
> 
> > On Wed, 24 Oct 2007, sun wrote:
> >
> >> Bear me if this is a naive question.
> >>
> >> I have a dataframe, all lists inside it are factors. When I use
> >
> > Do you mean 'all columns are factors'?  A data frame is a list but 
usually 
> > does not contain lists.
> >
> >> as.matrix(df) to convert, I get a character matrix while my intention 
is 
> >> to
> >> get numeric matrix. I can make the convertion  iteratively by each 
list 
> >> but
> >> I do think there is some more elegant way of doing this.
> >>
> >> please let me know if I missed somthing there.
> >
> > ?data.matrix  may be what you are looking for: you gave us too little 
> > detail to be sure.
> >
> 
> 
> Thanks for your helps. I did not provide data 'cause I thought this is 
FAQ 
> type of question(maybe wrong impression).
> Actually I use algdesign generated a factorial design data frame in 
which:
> >
> > str(dat)
> 'data.frame':   2304 obs. of  6 variables:
>  $ party : Factor w/ 3 levels "1","2","3": 1 2 3 1 2 3 1 2 3 1 ...
>  $ dinner: Factor w/ 3 levels "1","2","3": 1 1 1 2 2 2 3 3 3 1 ...
>  $ d1    : Factor w/ 4 levels "1","2","3","4": 1 1 1 1 1 1 1 1 1 2 ...
>  $ p1    : Factor w/ 4 levels "1","2","3","4": 1 1 1 1 1 1 1 1 1 1 ...
>  $ d2    : Factor w/ 4 levels "1","2","3","4": 1 1 1 1 1 1 1 1 1 1 ...
>  $ p2    : Factor w/ 4 levels "1","2","3","4": 1 1 1 1 1 1 1 1 1 1 ...
> 
> I just figured out a way fo convert it to numeric matrix using
> >d = as.data.frame(lapply(dat,as.numeric))
> 
> but "data.matrix()" suggested by Prof. Brian and Mr. Dimitris is exactly 
the 
> thing I was looking for.
> 
> I am not sure if there exist some documents or online source that have 
> documented these kind of "utility functions" categorized in somet 
categories 
> like "data types", "data manipulating functions", "variable scopes", 
etc., 
> that allow a quick browsing for some functions or other information.
> 

Try to look at Paul Johnson's StatsRus pages, which provide a collection 
of HowTo's. And maybe introduction to R manual in doc directory.

Regards
Petr

> Thanks for your kind helps.
> 
> Kind regards,
> Sun
> 
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