R help - Sep 2004 - function by

Hi,

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
Universit?? de Sherbrooke
2500 boul. de l'Universit??
Sherbrooke, Qu??bec
J1K 2R1 CANADA

T??l: 1-819-821-8000 poste 2059
Fax: 1-819-821-8049
Emilie.Berthiaume at USherbrooke.ca

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

...: further arguments to 'FUN'.


by (SS, year, sum)

/E



Emilie Berthiaume wrote:
>Hi,
>
>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
>Universit?? de Sherbrooke
>2500 boul. de l'Universit??
>Sherbrooke, Qu??bec
>J1K 2R1 CANADA
>
>T??l: 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
>https://stat.ethz.ch/mailman/listinfo/r-help
>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