R help - Aug 2003 - extract numerical variables from a data frame

Hi

I try to create from a data frame a new one which contains only the 
numerical variables (or factorial ones).

Is there any function which does this task directly ?
Or, is there any function which return the mode of each columns of a data 
frame. ?

Thanks a lot for any help you can offer me,

Vincent Spiesser

On Fri, 29 Aug 2003, Vincent Spiesser wrote:
> Hi
> 
> I try to create from a data frame a new one which contains only the 
> numerical variables (or factorial ones).
> 
> Is there any function which does this task directly ?
> Or, is there any function which return the mode of each columns of a data 
> frame. ?
I think you want the class, as in

sapply(adf, class)

You could use mode if you really wanted it, but watch out for e.g. the 
mode of a factor being "numeric".

However, for your original question I would use

numeric columns:

DF[sapply(DF, is.numeric)]

factor columns:

DF[sapply(DF, is.factor)]

and similar code is found throughout the R sources.

-- 
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

for data.frame called dframe:

newframe <- dframe[ , lapply(dframe, is.numeric)]

For the mode of the columns

lapply(dframe, mode)

See ?lapply !!
> -----Original Message-----
> From: Vincent Spiesser [mailto:Vincent.Spiesser at univ-tlse1.fr]
> Sent: 29 August 2003 10:08
> To: R-help at stat.math.ethz.ch
> Subject: [R] extract numerical variables from a data frame
> 
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> 
> Hi
> 
> I try to create from a data frame a new one which contains only the 
> numerical variables (or factorial ones).
> 
> Is there any function which does this task directly ?
> Or, is there any function which return the mode of each columns of a
> data 
> frame. ?
> 
> Thanks a lot for any help you can offer me,
> 
> Vincent Spiesser
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
>
 

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