Hi all, I have a problem with computing a new variable as an aggregated score of other variables. Say, I have 10 variables for 1,000 observations (people). Every variable may have values between 0 and 8. What I would like to do is computing the mean of the individual top 3 values for every person. Exampe: The values for the 10 variables (v1 to v10) for person A, B and C are as follows: A 0 1 0 2 5 8 3 0 4 0 B 6 4 3 0 0 0 0 5 0 0 C 0 0 8 0 0 8 0 0 0 0 So, I would like to compute a new variable for the mean of the individual top 3 values, which would result for person A, B and C in the following: A (8+5+4)/3 = 5.67 B (6+5+4)/3 = 5 C (8+8+0)/3 = 5.33 Is there any way to do this? Any clues, hints and suggestions are highly appreciated, many thanks in advance Johannes -- View this message in context: http://www.nabble.com/Problems-with-computing-an-aggregated-score-tp24495390p24495390.html Sent from the R help mailing list archive at Nabble.com.
On Wed, Jul 15, 2009 at 3:37 AM, Hatsch<johannes.heer at googlemail.com> wrote:> > Hi all, > > I have a problem with computing a new variable as an aggregated score of > other variables. > > Say, I have 10 variables for 1,000 observations (people). Every variable may > have values between 0 and 8. What I would like to do is computing the mean > of the individual top 3 values for every person. > > Exampe: The values for the 10 variables (v1 to v10) for person A, B and C > are as follows: > > A 0 1 0 2 5 8 3 0 4 0 > B 6 4 3 0 0 0 0 5 0 0 > C 0 0 8 0 0 8 0 0 0 0 > > So, I would like to compute a new variable for the mean of the individual > top 3 values, which would result for person A, B and C in the following: > > A (8+5+4)/3 = 5.67 > B (6+5+4)/3 = 5 > C (8+8+0)/3 = 5.33 > > Is there any way to do this? > > Any clues, hints and suggestions are highly appreciated, > many thanks in advance > JohannesUnquestionably the experienced guys are going to give you a better answer, but as a newbie I worked out a step by step answer in a few minutes. This allows you to see the steps: A <- c(0, 1, 0, 2, 5, 8, 3, 0, 4, 0) A[order(as.numeric(A), decreasing=TRUE)] A[order(as.numeric(A), decreasing=TRUE)][1:3] sum(A[order(as.numeric(A), decreasing=TRUE)][1:3]) sum(A[order(as.numeric(A), decreasing=TRUE)][1:3])/3 Hope this helps, Mark
Dear Johannes,
If 'x' is your data set, here is one way using apply:
res <- apply(x[,-1], 1, function(x){
xo <- sort(x, decreasing = TRUE)
mean(xo[1:3])
}
)
names(res) <- x[,1]
res
# A B C
# 5.666667 5.000000 5.333333
See ?apply, ?sort and ?mean for more information.
HTH,
Jorge
On Wed, Jul 15, 2009 at 6:37 AM, Hatsch
<johannes.heer@googlemail.com>wrote:
>
> Hi all,
>
> I have a problem with computing a new variable as an aggregated score of
> other variables.
>
> Say, I have 10 variables for 1,000 observations (people). Every variable
> may
> have values between 0 and 8. What I would like to do is computing the mean
> of the individual top 3 values for every person.
>
> Exampe: The values for the 10 variables (v1 to v10) for person A, B and C
> are as follows:
>
> A 0 1 0 2 5 8 3 0 4 0
> B 6 4 3 0 0 0 0 5 0 0
> C 0 0 8 0 0 8 0 0 0 0
>
> So, I would like to compute a new variable for the mean of the individual
> top 3 values, which would result for person A, B and C in the following:
>
> A (8+5+4)/3 = 5.67
> B (6+5+4)/3 = 5
> C (8+8+0)/3 = 5.33
>
> Is there any way to do this?
>
> Any clues, hints and suggestions are highly appreciated,
> many thanks in advance
> Johannes
> --
> View this message in context:
>
http://www.nabble.com/Problems-with-computing-an-aggregated-score-tp24495390p24495390.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org 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.
>
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