R help - Aug 2003 - Subsetting a dataframe

Hi R-people

I have a question concerning subsetting. I have a dataframe which contains among
other variables the variable "subject". For each subject number there
are several rows, e.g.:
subject  treatment concentration day
19          a          15,4       1
19          a          18,3       2
19          a           2,3       3

etc.

Im trying to subset the dataframe to get for example only the rows of subject 19
and subject 15. I tried this with

        nameofdataframe[nameofdataframe$subject==c(19,15),]

This doesnt work as i get less rows than i should and a warning as well. How can
i succeed doing this?

Thanks a lot

Gabi

Hi R-people

I have a question concerning subsetting. I have a dataframe which contains among
other variables the variable "subject". For each subject number there
are several rows, e.g.:
subject  treatment concentration day
19          a          15,4       1
19          a          18,3       2
19          a           2,3       3

etc.

Im trying to subset the dataframe to get for example only the rows of subject 19
and subject 15. I tried this with

        nameofdataframe[nameofdataframe$subject==c(19,15),]

This doesnt work as i get less rows than i should and a warning as well. How can
i succeed doing this?

Thanks a lot

Gabi

a0203664 at unet.univie.ac.at wrote:
> Hi R-people
> 
> I have a question concerning subsetting. I have a dataframe which contains
among other variables the variable "subject". For each subject number
there are several rows, e.g.:
> subject  treatment concentration day
> 19          a          15,4       1
> 19          a          18,3       2
> 19          a           2,3       3
> 
> etc.
> 
> Im trying to subset the dataframe to get for example only the rows of
subject 19 and subject 15. I tried this with
> 
>         nameofdataframe[nameofdataframe$subject==c(19,15),]
> 
> This doesnt work as i get less rows than i should and a warning as well.
How can i succeed doing this?
> 
> Thanks a lot
> 
> Gabi
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help

See ?"%in%"

as in

  nameofdataframe$subject %in% c(19,15)

Uwe Ligges

Or 

subset(nameofdataset, subject %in% c(15,19))

which does "the right thing" if subject should be missing (unlikely in
this
example I know, but likely to be a different story if conditioning on
concentration, say).

A pity subset() and transform() are not mentioned in the subsetting
section
of the "Introduction to R" manual - a suggestion for future releases?
 

Simon Fear
Senior Statistician
Syne qua non Ltd
Tel: +44 (0) 1379 644449
Fax: +44 (0) 1379 644445
email: Simon.Fear at synequanon.com
web: http://www.synequanon.com
 
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