[R] selecting only specific rows in R
Charles C. Berry
cberry at tajo.ucsd.edu
Sat Jun 5 19:10:27 CEST 2010
On Sat, 5 Jun 2010, stephen sefick wrote:
> 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...
> 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
Or use one of the built in datasets - there are several that pertain to
But yes, Adrienne, you should (as per Posting Guide) "provide commented,
minimal, self-contained, reproducible code".
> ?Orange # find out about 'Orange' tree dataset
> ## rows with more than one tree of a given circumference:
> subset( Orange, xtabs(~circumference)[ as.character(circumference) ] > 1
Tree age circumference
1 1 118 30
4 1 1004 115
6 1 1372 142
13 2 1372 203
14 2 1582 203
15 3 118 30
19 3 1231 115
29 5 118 30
33 5 1231 142
> # more detail to suggest why this works:
> with( Orange, xtabs(~circumference)[as.character(circumference)] > 1 )
> 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?
>> Adrienne Keller
>> R-help at r-project.org mailing list
>> 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 |
> | Department of Biological Sciences |
> | 331 Funchess Hall |
> | Auburn, Alabama |
> | 36849 |
> | sas0025 at auburn.edu |
> | http://www.auburn.edu/~sas0025 |
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods. We are mammals, and have not exhausted the
> annoying little problems of being mammals.
> -K. Mullis
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
Charles C. Berry (858) 534-2098
Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901
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