Hi:

Try this:

ratok <- data.frame(Id = rep(1:3, 3:1), value = c(2, 3, 4, 2, 1, 5))

aggregate(value ~ Id, data = ratok, FUN = mean)

Id value

1 1 3.0

2 2 1.5

3 3 5.0

aggregate() returns a data frame with the Id variable and mean(value).

HTH,

Dennis

On Sun, Oct 16, 2011 at 6:53 AM, Helene Schreyer

<

[hidden email]> wrote:

> Hello,

>

>

> I have a big problem which I’m just not able to solve.

>

>

>

> I created the following mean value from the following dataset structure:

>

>

> Id |value

>

> 1 | 2

>

> 1 | 3

>

> 1 | 4

>

> 2 | 2

>

> 2 | 1

>

> 3 | 5

>

> 4 | 3

>

> etc.|etc.

>

>

>

> with the command:

>

> mean_rating <- tapply(ratok$value, ratok$project_id , mean,simplify = FALSE)

>

>

>

> this gives me a ragged array:

>

>> mean_rating [1]

>

> $`14` ###########==project_id

>

> [1] 3.933333 #######==mean value

>

>

>

>

>

>> dim (mean_rating)

>

> [1] 2214

>

>

>

> I want to separate now the project_id from the mean value. So that I have

> two separate columns (2 dimension).

>

>

>

> How can I separate a ragged array into two variables?

>

>

>

>

>

>

>

> *Additional information:*

>

> I need this information to put the mean value into another dataset

> (“projok”) at the correct project_id.

>

>

>

> I would do that as follow:

>

> k=projok[,1]

>

>

>

> for(i in 1:2442) {

>

> projLineNb = which(mean_rating$project_id==k[i])

>

> projok$mean[i] = mean_rating$value[projLineNb]

>

> }

>

>

>

> But with a ragged array I can not refer to project_id. Or is there a

> possibility that I can refer to the project_id in a ragged array?

>

>

>

>> mean_rating [[1]]

>

> [1] 3.933333 ==I can refer to the value only

>

>

>

> Thank you very much

>

> Best,

>

> Helene

>

> [[alternative HTML version deleted]]

>

>

> ______________________________________________

>

[hidden email] 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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https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide

http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.