[R] combined multiple observations

[Gabor Grothendieck]

Assuming DF is your data frame, try this:

   aggregate(DF[,0-1:2], DF[,1:2], sum)


On 5/4/06, YIHSU CHEN <yschen at jhu.edu> wrote:
> Dear R users:
>
> I have a data frame as follows, where e1-e3 are indicator variables with value equal 0 or 1.
>
> St  County  e1 e2 e3
> 1   2             1   0   0
> 1   2             0   1   0
> 2   1             0   0   1
> 2   2             1   0   0
>
> What I would like to do is to combine observations with same pair of "ST" and "County" together.  For example, for the St=1 and County=2, I would like to have follows:
>
> St  County  e1 e2 e3
> 1   2             1   1   0
>
> Since I have a total of more than 30000 observations, any blue force way seems to be not efficient.  Does anyone of you have experience to deal with it?
>
> Thank you so much.
>
>
> Yihsu Chen
> The Johns Hopkins University
>
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