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

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