R help - Oct 2007 - convert factor dataframe into numeric matrix

Bear me if this is a naive question.

I have a dataframe, all lists inside it are factors. When I use 
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.

 Thanks in advance.

Sun

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.

-- 
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

look at ?data.matrix().

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "sun" <flyhyena at yahoo.com.cn>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, October 24, 2007 2:51 PM
Subject: [R] convert factor dataframe into numeric matrix

> Bear me if this is a naive question.
>
> I have a dataframe, all lists inside it are factors. When I use
> 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.
>
> Thanks in advance.
>
> Sun
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

Hi

r-help-bounces at r-project.org napsal dne 24.10.2007 14:51:10:
> Bear me if this is a naive question.
> 
> I have a dataframe, all lists inside it are factors. When I use 
> 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.
You missed to provide several information, mainly some example.

1.      How did you get nonumeric data frame? If it is by transfer from 
Excel or something like that, you definitelly shall look at raw data as 
there is some mismatch. R tries to keep numeric as numeric but converts 
character to factor.
2.      Are the values numeric? I presume that yes. So you can use e.g. 
sapply

 sapply(dat, function(x) as.numeric(as.character(x)))

Regards
Petr
> 
>  Thanks in advance.
> 
> Sun
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.