[R] getting a weighted average from a table
Phil Spector
spector at stat.berkeley.edu
Fri May 7 17:48:36 CEST 2010
dat = c(1.3,1.2,1,3.3,3.3,5.1,1.1,1.2,0)
tt = table(dat)
sum(as.numeric(names(tt))*tt)/ sum(tt)
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spector at stat.berkeley.edu
On Fri, 7 May 2010, SHANE MILLER, BLOOMBERG/ 731 LEXIN wrote:
> Hi,
>
> I have a very simple request (I think).
> I have a vector/array,
>
> > c <- c(1.3,1.2,1,3.3,3.3,5.1,1.1,1.2,0)
>
> I produce a reverse sorted table/histogram with it,
>
> > t = rev(sort(table(c))
> > t
> c
> 3.3 1.2 5.1 1.3 1.1 1 0
> 2 2 1 1 1 1 1
>
> I would now like to get the labels "3.3 1.2 5.1 1.3 1.1 1 0"
> into its own vector and the # of counts "2 2 1 1 1 1 1"
> so I can calculate weighted averages. So if I can get the labels into
> a vector l and the counts into a vector n,
>
> l <- c(3.3,1.2,5.1,1.3,1.1,1,0);
> n <- c(2,2,1,1,1,1,1);
>
> for(i=0;i<7;i++)
> total = l[i]*n[i]
> total = total / sum(n) <- this is the weight average
>
>
>
>
>
>
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