[R] the first and last case

[Carlos J. Gil Bellosta]

Dear Jacques,

I believe you need dat ordered by ind and y before you apply your solution,
right?

Sincerely,

Carlos J. Gil Bellosta
http://www.datanalytics.com
http://www.data-mining-blog.com

Quoting Jacques VESLOT <jacques.veslot at good.ibl.fr>:

> do.call(rbind,lapply(split(dat, dat$ind), function(x) x[c(1,nrow(x)),]))
> -------------------------------------------------------------------
> Jacques VESLOT
>
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>
> Mauricio Cardeal a écrit :
>> Hi all
>>
>> Sometime ago I asked for a solution about how to aggregate data and the
>> help was wonderful. Now, I´d like to know how to extract for each
>> individual case below the first and the last observation to obtain this:
>>
>> ind  y
>> 1    8
>> 1    9
>> 2    7
>> 2   11
>> 3    9
>> 3   10
>> 4   8
>> 4   5
>>
>> # Below the example:
>>
>> ind <- c(1,1,1,2,2,3,3,3,4,4,4,4)
>> y <- c(8,10,9,7,11,9,9,10,8,7,6,5)
>> dat <- as.data.frame(cbind(ind,y))
>> dat
>> attach(dat)
>> mean.ind <- aggregate(dat$y, by=list(dat$ind), mean)
>> mean.ind
>>
>> Thanks
>> Mauricio
>>
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>>
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>