Ah perfect thank you.
________________________________
From: jholtman [via R] [mailto:[email protected]]
Sent: Tuesday, February 23, 2010 2:00 PM
To: ROLL Josh F
Subject: Re: select row based on highest value
Is this better:
> sapply(split(v, v$Prop), function(x) x$TAZ[which.max(x$area)])
p754921 p75506 p75508
37 282 46
>
Take a look at what you were doing. The result of the 'tapply' is to
split v$area in to smaller groups based on v$Prop, so the 'x'
parameter is not going to be the same length as your 'v' dataframe and
therefore you are indexing to the incorrect value. Best to split the
dataframe and then operate on the individual portions.
On Tue, Feb 23, 2010 at 3:47 PM, LCOG1 <[hidden
email]<http://n4.nabble.com/user/SendEmail.jtp?type=node&node=1566613&i=0>>
wrote:
>
> Please consider the following
>
> #Data to use
> Props<-c("p754921","p754921" ,"p754921","p75506" ,"p75506"
> ,"p75506","p75506","p75508","p75508","p75508","p75508","p75508")
> TAZ<-c(38,37,37,171,171,282,171,46,46,169,169,169)
> Area<-c(109828.04, 128134.71, 46469.57, 37160.21,
> 40080.50,344679.66,16972.28,
> 342309.558, 260906.870, 17014.659, 7285.706, 10936.316)
>
> TazProperties..<-data.frame(Props,TAZ,Area)
>
>
> t <- TazProperties..
> v <- aggregate(t$Area, by=list(t$TAZ,t$Props), sum)
> names(v) <- c("TAZ", "Prop", "area")
> a<-tapply(v$area, v$Prop, function(x) v$TAZ[which.max(x)])
>
> "a" returns:
>
> p754921 p75506 p75508
> 37 38 37
>
> and it should return
>
> p754921 p75506 p75508
> 37 282 46
>
> What am i doing wrong? Thanks
> --
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>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
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