[R] Doing SQL GROUP BY in R

[Pierre Kleiber]

Assuming you have a data.frame, dat, with coluns A and B, I think what you 
want would be:

 > table(paste(dat$A,dat$B))


JFRI (Jesper Frickmann) wrote:
> I want a list of the number of times some factor levels appear together,
> similar to the following SQL statement:
> 
> SELECT A, B, COUNT(C) FROM TBL GROUP BY A, B
> 
> How do I do that with a data.frame in R?
> 
> Thanks,
> Jesper Frickmann
> Statistician, Quality Control
> Novozymes North America Inc.
> 77 Perry Chapel Church Road
> Franklinton, NC 27525
> USA
> Tel. +1 919 494 3266
> 
> 
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> 
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Pierre Kleiber, Ph.D       Email: pkleiber at honlab.nmfs.hawaii.edu
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