Hi R experts,

I need know how calculate a weighted mean by group in a data frame. I have
tried with aggragate() function:

data.frame(x=c(15,12,3,10,10),g=c(1,1,1,2,2,3,3),w=c(2,3,1,5,5,2,5)) -> d
aggregate(d$x,by=list(d$g),weighted.mean,w=d$w)

Generating the following error:

Error en FUN(X[[1L]], ...) : 'x' and 'w' must have the same length

Thanks in advance

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