Hi JR,
There are few ways to do what you asked for, so here is one suggestion using
tapply:

Age <- c(48, 57, 56, 76, 76, 66, 70, 14,  7,  3, 62, 62, 30, 10,  7, 53, 44,
29, 46, 47, 15, 13, 84, 77, 26)

SerialNo <- c(001147, 005979, 005979, 006128, 006128, 007004, 007004,
007004,
007004, 007004, 007438, 007438,009402,009402, 009402, 012693, 012693,
012693, 014063,014063, 014063, 014063, 014811, 014811,016570)

TestSet <- data.frame(Age,SerialNo)
TestSet$IsHead <-  do.call(c, tapply(Age, SerialNo, function(x) x >= max(x)
) )
TestSet

See ?tapply, ?do.call as well as ?ave for more information.

HTH,

Jorge



On Mon, Aug 3, 2009 at 3:04 PM, PDXRugger <> wrote:

>
> COnsider the following:
>
> Age<-c(48, 57, 56, 76, 76, 66, 70, 14,  7,  3, 62, 62, 30, 10,  7, 53, 44,
> 29, 46, 47, 15, 13, 84, 77, 26)
>
> SerialNo<-c(001147, 005979, 005979, 006128, 006128, 007004, 007004, 007004,
> 007004, 007004, 007438, 007438,009402,009402, 009402, 012693, 012693,
> 012693, 014063,014063, 014063, 014063, 014811, 014811,016570)
>
> TestSet<-cbind(Age,SerialNo)
>
> TestSet<-data.frame(TestSet)
>
> I am looking to create a third column titled "IsHead".  This column would
> be
> either TRUE or FALSE depending on whether the Age variable was the greatest
> for that set of SerialNo's.  So for the above i would return:
>
> Age     SerialNo  IsHead
> 48      1147          TRUE
> 57      5979          TRUE
> 56      5979          FALSE
> 76      6128          TRUE
> 76      6128           FALSE
> 66      7004          FALSE
> 70      7004          TRUE
> 14      7004          FALSE
> 7       7004          FALSE
> 3       7004          FALSE
>
> I am thinking this is simple but cannot get my own code to work.  Thanks
> for
> any insights.
>
> JR
> --
> View this message in context:
> http://www.nabble.com/Truncating-based-on-attribute-range-and-serial-no-tp24796313p24796313.html
> Sent from the R help mailing list archive at Nabble.com.
>
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