[R] average by group...

[Peter Dalgaard]

"Doran, Harold" <HDoran at air.org> writes:

> ?tapply

Nope. 

?ave
  
> 
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch 
> > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of r user
> > Sent: Tuesday, May 30, 2006 12:27 PM
> > To: rhelp
> > Subject: [R] average by group...
> > 
> > I have a dataframe with 700,000 rows and 2 vectors
> > (columns): "group" and "score".
> > 
> > I  wish to calculate a third vector of length 700000:
                                        ^^^^^^^^^^^^^^^^

> > the average score by group.  Even though the avarge value 
> > will repeat, I wish to return the average for that particular 
> > group for each row.
> > 
> > (I know I can do this by calculating each group's average and 
> > then using the merge command, but as my calculations get more 
> > complex and my data set gets larger, the merge command seems 
> > to be fairly slow.)
> > 
> > ______________________________________________
> > 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
> >
> 
> ______________________________________________
> 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
> 

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907