See the examples labelled head in the examples section near the bottom of:
http://sqldf.googlecode.com/svn/trunk/man/sqldf.Rd
These show show to do it using order as well as using SQL via sqldf.
On 8/31/07, Cory Nissen <[EMAIL PROTECTED]> wrote:
> I am working with census data. My columns of interest are...
>
> PercentOld - the percentage of people in each county that are over 65
> County - the county in each state
> State - the state in the US
>
> There are about 3100 rows, with each row corresponding to a county within a
> state.
>
> I want to return the top five "PercentOld" by state. But I want the County
> and the Value.
>
> I tried this...
>
> topN <- function(column, n=5)
> {
> column <- sort(column, decreasing=T)
> return(column[1:n])
> }
> top5PerState <- tapply(data$percentOld, data$STATE, topN)
>
> But this only returns the value for "percentOld" per state, I also want the
> corresponding County.
>
> I think I'm close, but I just can't get it...
>
> Thanks
>
> cn
>
> [[alternative HTML version deleted]]
>
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