[R] function by

Witold Eryk Wolski wolski at molgen.mpg.de
Thu Sep 30 18:21:23 CEST 2004

FUN: a function to be applied to data frame subsets of 'data'.

...: further arguments to 'FUN'.

by (SS, year, sum)


Emilie Berthiaume wrote:

>I'm just getting started with R and I'm having problems with some simple
>operations: I want to get the the sum of the column "SStot" for each year using
>the function by.  The data set is named "SS".  I've tried this:
>by (SS, year, sum(SStot))
>and it's not working.  Is it because there's a different number of rows for each
>year?  How else can I do this?
>Emilie Berthiaume
>Graduate student
>Biology Departement
>Université de Sherbrooke
>2500 boul. de l'Université
>Sherbrooke, Québec
>Tél: 1-819-821-8000 poste 2059
>Fax: 1-819-821-8049
>Emilie.Berthiaume at USherbrooke.ca
>R-help at stat.math.ethz.ch mailing list
>PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

Dipl. bio-chem. Witold Eryk Wolski         
MPI-Moleculare Genetic
Ihnestrasse 63-73 14195 Berlin           _
tel: 0049-30-83875219                   'v'
http://www.molgen.mpg.de/~wolski       /   \
mail: witek96 at users.sourceforge.net  ---W-W----
      wolski at molgen.mpg.de

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