On 7/23/2009 5:18 PM, Alexis Maluendas wrote:
> 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$w)
>
> Generating the following error:
>
> Error en FUN(X[[1L]], ...) : 'x' and 'w' must have the same length
DF <- data.frame(x=c(15,12, 3,10,10,14,12),
g=c( 1, 1, 1, 2, 2, 3, 3),
w=c( 2, 3, 1, 5, 5, 2, 5))
sapply(split(DF, DF$g), function(x){weighted.mean(x$x, x$w)})
1 2 3
11.50000 10.00000 12.57143
> Thanks in advance
>
> [[alternative HTML version deleted]]
>
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