[R] Using "mean" if two values are identical

Julien Barnier jbarnier at ens-lsh.fr
Thu Apr 19 16:11:34 CEST 2007


> I've got a matrix (mail end) with the colnames x, y, z. In this matrix
> are different measurements. x and y are risign coordinates.
> My question. Always, if the "x" AND "y" coordinates are the same, I want to 
> get the mean of their z values.

Maybe you could try with the aggregate function, for example  :

aggregate(INPUT[,3], by=list(INPUT[,1],INPUT[,2]), FUN=mean)

Hope that helps,
Julien Barnier
Groupe de recherche sur la socialisation
ENS-LSH - Lyon, France

More information about the R-help mailing list