R help - Feb 2013 - how to

Dear List,

I have a list of lists and on each list I want to apply a function
from the igraph package, graph.knn. I need to calculate graph.knn for
each list on a graph g, then retrieve one of the result called $knn
and calculate its mean. The non-R style code looks like this:

for(i in listOfLists){
	print(mean(graph.knn(g, i)$knn))
}

Is there any way to convert this in a one-liner? I have tried to
figure it out with lapply() or mapply() but with no success.

Thank you in advance for your help.

Simone

-- 
Simone Gabbriellini, PhD

PostDoc at DISI, University of Bologna
mobile: +39 340 39 75 626
email: simone.gabbriellini at unibo.it
home: www.digitaldust.it

DigitalBrains srl
Amministratore
mobile: +39 340 39 75 626
email: simone.gabbriellini at digitalbrains.it
home: www.digitalbrains.it

Hi

I do not see any problem with your code. *apply functions are also hidden cycles
and there shall not be substantial improvement in speed.

Why you do not want to use for cycle?

Petr

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Simone Gabbriellini
> Sent: Friday, February 01, 2013 12:54 PM
> To: r-help at r-project.org
> Subject: [R] how to
> 
> Dear List,
> 
> I have a list of lists and on each list I want to apply a function from
> the igraph package, graph.knn. I need to calculate graph.knn for each
> list on a graph g, then retrieve one of the result called $knn and
> calculate its mean. The non-R style code looks like this:
> 
> for(i in listOfLists){
> 	print(mean(graph.knn(g, i)$knn))
> }
> 
> Is there any way to convert this in a one-liner? I have tried to figure
> it out with lapply() or mapply() but with no success.
> 
> Thank you in advance for your help.
> 
> Simone
> 
> --
> Simone Gabbriellini, PhD
> 
> PostDoc at DISI, University of Bologna
> mobile: +39 340 39 75 626
> email: simone.gabbriellini at unibo.it
> home: www.digitaldust.it
> 
> DigitalBrains srl
> Amministratore
> mobile: +39 340 39 75 626
> email: simone.gabbriellini at digitalbrains.it
> home: www.digitalbrains.it
> 
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