If you sort the data by id and then by month I think your code will
work. Look at the following example based on your data:
***** Stata Example Begin *****
clear
input byte id byte value byte month
1 25 12
1 22 8
2 30 9
3 28 8
3 24 6
end
list
sort id month
list
drop if id==id[_n-1]
list
***** Stata Example End *****
Best,
Alan
On Thu, Nov 13, 2008 at 4:33 PM, Rijo John <[email protected]> wrote:
> Dear Statalist,
>
> I have some repeated observations that I need to drop. I have defined
> a unique ID variable. There are two other variables "value" and
> "month" for these IDs.
>
> Example data.
>
> ID Value month
> 1 25 12
> 1 22 8
> 2 30 9
> 3 28 8
> 3 24 6
>
>
> Only few IDs are repeated in the actual data.
>
> Basically I need to retain only one value per ID. If I do "drop if
> ID==ID[_n-1]" after sorting the IDs it could drop any of the values.
> But I want the data to retain those values where in month takes the
> highest value when I am dropping ID==ID[_n-1]. Something like
>
> drop min(month, month[_n-1]) if ID==ID[_n-1] is what I am looking for.
> However, I cant use such time series operators with min function. Any
> thoughts?
>
> Regards,
> Rijo.
> *
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