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Re: st: Insert new observation by group


From   Austin Nichols <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Insert new observation by group
Date   Wed, 2 Nov 2011 17:22:32 -0400

Fernando Luco <flucoestatalist@gmail.com> :

clear
input group y  x
1       1       10
1       2       10
1       2       10
2       3       8
2       1       8
end
g obs=_n
bys group x: g e=1+(_N==_n)
expand e
bys group x (obs): replace y=. if _n==_N
by group x: g sumy=sum(y)
replace y=x-sumy if mi(y)
list, sepby(group)


On Wed, Nov 2, 2011 at 5:13 PM, Fernando Luco <flucoestatalist@gmail.com> wrote:
> Dear all,
>
> I'm trying to create a new observation for each group in my data, but
> I haven't been able to do so. I tried using -ingap- but didn't work
> because
> it inserts the new observation at the top of the group or after the
> first observation.
> My data looks as follows:
>
> group y  x
> 1       1       10
> 1       2       10
> 1       2       10
> 2       3       8
> 2       1       8
>
> What I want is to insert a new observation at the end of each group,
> and this observation must be the difference between "x" (in my case
> this is 10 for group one and 8 for group two) and the sum of "y"
> (6 for group one and 3 for group two). So, the idea is that the final
> dataset should look as follows
>
> group y x
> 1       1       10
> 1       2       10
> 1       2       10
> 1      5       10
> 2       3       8
> 2       1       8
> 2      4       8
>
> Any ideas? Thanks,
>
> Fernando
> *
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>

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