[R] weighted mean by week

Dimitri Liakhovitski dimitri.liakhovitski at gmail.com
Wed Jul 18 19:07:53 CEST 2012

David, thanks a lot!
I tried x[-1] myself but forgot to delete 'group' from the keyby
statement - this explains why it did not work for me.
This is amazing - just 2 lines instead of my many-many.
Great learning!

On Tue, Jul 17, 2012 at 10:49 PM, David Freedman <dxf1 at cdc.gov> wrote:
> Honestly, I wasn't sure what you wanted to do with 'group'.  Here it is with
> the 'group' variable deleted
> library(data.table)
> dt=data.table(x[,-1])
> dt[,lapply(.SD, function(x)weighted.mean(x,myweight)), keyby='myweek']
> --
> View this message in context: http://r.789695.n4.nabble.com/weighted-mean-by-week-tp4636814p4636828.html
> Sent from the R help mailing list archive at Nabble.com.
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Dimitri Liakhovitski

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