Dimitris Rizopoulos wrote: > you need also to split the 'w' column, for each level of 'x'; you > could use: > > lapply(split(truc, truc$x), function(z) weighted.mean(z$y, z$w)) > > > I hope it helps. > > Best, > Dimitris
Or: library(Hmisc) ?wtd.mean The help file has a built-in example of this. Frank > > ---- > Dimitris Rizopoulos > Ph.D. Student > Biostatistical Centre > School of Public Health > Catholic University of Leuven > > Address: Kapucijnenvoer 35, Leuven, Belgium > Tel: +32/(0)16/336899 > Fax: +32/(0)16/337015 > Web: http://www.med.kuleuven.be/biostat/ > http://www.student.kuleuven.be/~m0390867/dimitris.htm > > > > ----- Original Message ----- > From: "Florent Bresson" <[EMAIL PROTECTED]> > To: "R-help" <[email protected]> > Sent: Thursday, January 12, 2006 3:44 PM > Subject: [R] tapply and weighted means > > > >>I' m trying to compute weighted mean on different >>groups but it only returns NA. If I use the following >>data.frame truc: >> >>x y w >>1 1 1 >>1 2 2 >>1 3 1 >>1 4 2 >>0 2 1 >>0 3 2 >>0 4 1 >>0 5 1 >> >>where x is a factor, and then use the command : >> >>tapply(truc$y,list(truc$x),wtd.mean, weights=truc$w) >> >>I just get NA. What's the problem ? What can I do ? >> >>______________________________________________ >>[email protected] mailing list >>https://stat.ethz.ch/mailman/listinfo/r-help >>PLEASE do read the posting guide! >>http://www.R-project.org/posting-guide.html >> > > > > Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > -- Frank E Harrell Jr Professor and Chair School of Medicine Department of Biostatistics Vanderbilt University ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
