[R] Count values in a dataframe with respect to groups

[ONKELINX, Thierry]

Have a look at table

table(na.omit(dta)$grp)

Untested!

------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen
Belgium

Research Institute for Nature and Forest
team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium

tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of
data.
~ John Tukey
  

> -----Oorspronkelijk bericht-----
> Van: r-help-bounces op r-project.org 
> [mailto:r-help-bounces op r-project.org] Namens Marcus Drescher
> Verzonden: vrijdag 8 oktober 2010 16:29
> Aan: r-help op r-project.org
> Onderwerp: [R] Count values in a dataframe with respect to groups
> 
> Dear all,
> 
> I am looking for a function to count values belonging to a 
> class within a dataframe (and ignore NAs).
> 
> grp = c(1,1,1, 1,2, 2,2)
> val = c(2,1,5,NA,3,NA,1)
> 
> dta = data.frame(grp=grp, val=val)
> 
> The result should look like:
> 
> grp count
>  1    3
>  2    2
> 
> At the moment, I am trying to find a function for FUN in 
> aggregate, but with no success. Can anybody help me?
> 
> Thanks in advance.
> Marcus
> 
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