[R] apply over parallel lists and their elements

[Liviu Andronic]

Hello

On Sun, Sep 12, 2010 at 5:37 PM, Sebastian Gibb <lists at sebastiangibb.de> wrote:
> Hello,
>
> thanks for your answer.
> mapply fits to my needs.
>
One thing that seems strange is that if you use
tree[[1]]$node$values <- 1:10
tree[[2]]$node$values <- 3:12

you still get
> mapply(mean, tree[[1]]$node$values, tree[[2]]$node$values)
 [1]  1  2  3  4  5  6  7  8  9 10

But I cannot understand what's wrong.


> But I don't know how many items would "tree" have. I can't write them all by
> hand.
> How can I generate the arguments for mapply?
>
Unfortunately I cannot think of a solution. Perhaps reorganise your
data, so that all relevant data points go into the same vector. For
example,
tree[[4]]<-list();
tree[[4]][['node']]<-list();
tree[[4]]$node$more[[1]] <- 1:10
tree[[4]]$node$more[[2]] <- 3:12
> mapply(mean, tree[[4]]$node$more)
[1] 5.5 7.5

Also check maply and mlply to see if they can fit your needs. [1] Regards
Liviu

[1] http://had.co.nz/plyr/plyr-intro-090510.pdf



> mapply(mean, tree[[1]]$node$values, tree[[2]]$node$values, ...
> tree[[k]]$node$values);
>
> Kind regards,
>
> Sebastian
>
> ______________________________________________
> R-help at 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.
>



-- 
Do you know how to read?
http://www.alienetworks.com/srtest.cfm
http://goodies.xfce.org/projects/applications/xfce4-dict#speed-reader
Do you know how to write?
http://garbl.home.comcast.net/~garbl/stylemanual/e.htm#e-mail