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Re: st: Aggregate different parts of data selectively
From
Nick Cox <[email protected]>
To
"[email protected]" <[email protected]>
Subject
Re: st: Aggregate different parts of data selectively
Date
Mon, 3 Feb 2014 19:33:00 +0000
Your example is rather mysterious but you could
keep if (group == 1 & no > 2) | (group == 2 & no > 5) | (group == 3 & no > 3)
after which -collapse- would work on all specified observations.
Nick
[email protected]
On 3 February 2014 19:24, Chris Yang <[email protected]> wrote:
> Dear All,
>
> I have a dataset of the following structure:
>
> group no var1 var2 var3
> 1 1 3 2 1
> 1 2 2 0 0
> 1 3 3 0 1
> 1 4 0 1 1
> 1 5 1 1 2
> ...
> 2 1 3 2 1
> 2 2 3 0 0
> 2 3 1 1 1
> 2 4 0 2 1
> 2 5 0 0 2
> ...
> 3 1 1 1 1
> 3 2 2 3 1
> 3 3 2 1 1
> ...
>
> I want to aggregate a subset of observations by group, e.g. aggregate
> (using the mean) all the observations with `no` > 2 in group 1,
> aggregate observations with `no` > 5 in group 2, aggregate
> observations with `no` > 3 in group 3, and so on. And carry out
> analysis using the aggregated data of different groups only.
>
> I know that --collapse-- can do the averaging job within each group,
> however, it will also replace all existing data with the aggregated
> data. In my case, it would mean that I lose the data for all the other
> groups once I collapse/aggregate for any single group.
>
> A tedious way is to collapse and save respective groups individually,
> and then merge the aggregated per-group data in the end. I wonder if
> there is a more efficient way to achieve my goal here?
>
> Your thoughts and suggestions are appreciated. Thanks.
>
> Best regards,
>
> Chris
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