R help - Jun 2010 - selecting only specific rows in R

Hi, I have a data frame with columns as follows: tree species  
(independent variable) and several dependent variables (e.g. carbon,  
nitrogen, phosphorus). Each row represents one tree sample. Some tree  
samples are unique species in the data frame while other species were  
replicated (i.e. rows 1,2,3 may be identical for the "tree species"  
column but have different values for the other dependent variable  
columns). I want to create a new data frame that selects only the tree  
species that have replicates. In other words, I want to select all  
rows that have at least one replicate in the column "tree species".

Ideas on how to write such a function?

Thanks,

Adrienne Keller

Reproducible dummy example, as to the posting guide.  look at unique-
you want to subset the data frame on all of the non-unique entries in
the species column...

x[x!=unique(x[,"species"]),]

Something like that, maybe.  If I had some data then I could probably
figure it out.  Use dput() or fake data to make a cut and paste-able
example.
HTH,

Stephen

On Sat, Jun 5, 2010 at 10:00 AM, Adrienne Keller
<adrienne.keller at umontana.edu> wrote:
> Hi, I have a data frame with columns as follows: tree species (independent
> variable) and several dependent variables (e.g. carbon, nitrogen,
> phosphorus). Each row represents one tree sample. Some tree samples are
> unique species in the data frame while other species were replicated (i.e.
> rows 1,2,3 may be identical for the "tree species" column but
have different
> values for the other dependent variable columns). I want to create a new
> data frame that selects only the tree species that have replicates. In
other
> words, I want to select all rows that have at least one replicate in the
> column "tree species".
>
> Ideas on how to write such a function?
>
> Thanks,
>
> Adrienne Keller
>
> ______________________________________________
> 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.
>


-- 
Stephen Sefick
____________________________________
| Auburn University                                   |
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| sas0025 at auburn.edu                             |
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|___________________________________|

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