Alternatively, this looks like a -collapse-
or even a -contract-.
Nick
n.j.cox@durham.ac.uk
Ulrich Kohler
> How about:
>
> by pref1 pref2, sort: replace wgt = sum(wgt)
> by pref1 pref2: keep if _n == _N
Dietrich Drüner
> > I need to aggregate the number of observations in my data
> set when they
> > have identical values on two variables AND I need to sum
> up the values of a
> > third variable so that it remains the same for the
> reduced data set. I will
> > try to illustrate this and also describe the substantial problem:
> >
> > my initial data matrix looks like this:
> >
> > act wgt pref1 pref2
> > 1 4 100 0
> > 2 5 33 0
> > 3 3 33 50
> > 4 3 100 50
> > 5 10 33 0
> > 6 10 33 100
> > 7 5 33 50
> > 8 3 33 50
> > 9 10 33 50
> > 10 2 33 50
> > 11 5 33 0
> > 12 5 33 50
> > 13 8 33 50
> > 14 4 100 0
> > 15 10 33 50
> > 16 100 70
> > 17 100 70
> >
> > sum 87
> >
> > The first variable is the number of my actors (the 15 EU
> member states plus
> > the European Commission and the European Parliament). The
> second variable
> > is the voting weights of the member states. The third and
> fourth variables
> > are preferences of the actors in two dimensions. Many of
> the actors have
> > identical preference profiles that I need to aggregate.
> >
> > The result of this aggregation should look like this:
> >
> > act wgt pref1 pref2
> > 1 8 100 0
> > 2 20 33 0
> > 3 46 33 50
> > 4 3 100 50
> > 5 10 33 100
> > 6 100 70
> >
> > sum 87
> >
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