Try this:
> fdata
state statenum year income popul
1 ALABAMA 1 1 9.703193 3973
2 ALABAMA 1 2 9.745950 3992
3 ALABAMA 1 3 9.762092 4015
4 ALASKA 2 1 10.221640 532
5 ALASKA 2 2 10.169600 544
6 ALASKA 2 3 10.101300 539
> statepops<-tapply(fdata$popul,fdata$state,sum)
> popweight <- statepops/sum(statepops)
> fdata$adj <- fdata$income * popweight[fdata$state]
> fdata
state statenum year income popul adj
1 ALABAMA 1 1 9.703193 3973 8.550515
2 ALABAMA 1 2 9.745950 3992 8.588193
3 ALABAMA 1 3 9.762092 4015 8.602417
4 ALASKA 2 1 10.221640 532 1.214266
5 ALASKA 2 2 10.169600 544 1.208084
6 ALASKA 2 3 10.101300 539 1.199971
>
On Tue, Jun 23, 2009 at 3:11 PM, camillus <citizencamil...@gmail.com> wrote:
>
> Hi Guys,
>
> I would like to weight column entries in a data frame by the population of
> each state. For example, here is some data:
>
> state statenum year income popul
> ALABAMA 1 1 9.703193 3973.00
> ALABAMA 1 2 9.745950 3992.00
> ALABAMA 1 3 9.762092 4015.00
> ALASKA 2 1 10.221640 532.00
> ALASKA 2 2 10.169600 544.00
> ALASKA 2 3 10.101300 539.00
>
>
> I would like to adjust "income" by population ("popul") for each state. I
> can use:
>
> statepop<-tapply(fdata$popul,fdata$state,sum),
>
> which gives:
>
> ALABAMA ALASKA
> 53590.130 7435.263
>
> I can find the weights:
>
> popweight <- statepops/sum(statepops)
>
> ALABAMA ALASKA
> 0.016327564 0.002265338
>
> Is there an efficient way to multiply each entry of "income" by "popweght"
> conditional on the state? That is, ALABAMA income for year 1 is
> 9.703193*0.016327564, etc.
>
> Thanks,
>
> William
> --
> View this message in context:
> http://www.nabble.com/Weighting-column-entries-in-a-data-frame-tp24171435p24171435.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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