[R] question: ragged array

[Dennis Murphy]

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
<helene.schreyer at gmail.com> 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]]
>
>
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