Hi Trever,
You can do it like this:

count <- function(x) {
  length(na.omit(x))
}

counts <-
data.frame(aggregate(mydata[,4:5],by=list(mydata$userid),FUN="count"))

-Ista

On Fri, Apr 16, 2010 at 10:35 AM, KDT <dkadengye@gmail.com> wrote:

>
> Dear R-Users,
> I have a big data set "mydata" with repeated observation and some missing
> values. It looks like the format below:
>
> userid sex item score1  score2
> 1         0    1      1         1
> 1         0    2      0         1
> 1         0    3      NA       1
> 1         0    4      1         0
> 2         1    1      0         1
> 2         1    2      NA       1
> 2         1    3      1         NA
> 2         1    4      NA       0
> 3         0    1      1         0
> 3         0    2      1         NA
> 3         0    3      1         0
> 3         0    4      0         0
>
> I wound like to summarise the dataset such that i get something in the
> format of
>
> userid sumscore1  countscore1  meanscore1 sumscore2  countscore2
> meanscore2
> 1          2                    3            0.67              3
> 4              0.75
> 2          1                    2            0.5                2
> 3               0.67
> 3          3                    4            0.75              0
> 3               0.00
>
> I tried using :
> means <- data.frame(aggregate(mydata[,
> 4:5],by=list(mydata$userid),FUN="mean", na.rm="TRUE"))
> and
> sums <- data.frame(aggregate(mydata[,
> 4:5],by=list(mydata$userid),FUN="sum",
> na.rm="TRUE"))
>
> so that i could merge the two data.frames later. This works quite okay but
> i
> still can not get a function that can give me a data.frame for the counts!!
> Something like this::
> counts <- data.frame(aggregate(mydata[,
> 4:5],by=list(mydata$userid),FUN="count", na.rm="TRUE")).
>
> Any advice?
>
> Trevor
> Belgium
>
> --
> View this message in context:
> http://n4.nabble.com/score-counts-in-an-aggregate-function-tp2007152p2007152.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.
>



-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org

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