Re: [R] Assignments inside lapply

From: ONKELINX, Thierry <Thierry.ONKELINX_at_inbo.be>
Date: Wed, 27 Apr 2011 10:06:07 +0000

Dear Alex,

I think you want to use apply()

ij <- expand.grid(i = seq_len(dimx),j = seq_len(dimy)) Powermap <- apply(ij, 1, function(x){

        Pr(x, c(PRX, PRY), f)
})

Best regards,

Thierry



ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek
team Biometrie & Kwaliteitszorg
Gaverstraat 4
9500 Geraardsbergen
Belgium

Research Institute for Nature and Forest team Biometrics & Quality Assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium

tel. + 32 54/436 185
Thierry.Onkelinx_at_inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey   

> -----Oorspronkelijk bericht-----
> Van: r-help-bounces@r-project.org
> [mailto:r-help-bounces_at_r-project.org] Namens Alaios
> Verzonden: woensdag 27 april 2011 11:37
> Aan: R-help_at_r-project.org
> Onderwerp: [R] Assignments inside lapply
>
> Dear all I would like to ask you if an assignment can be done
> inside a lapply statement.
>
> For example
>
> I would like to covert a double nested for loop
>
> for (i in c(1:dimx)){
> for (j in c(1:dimy)){
> Powermap[i,j] <- Pr(c(i,j),c(PRX,PRY),f)
> }
> }
>
> to something like that:
>
>
> ij<-expand.grid(i=seq(1:dimx),j=(1:dimy))
>
> unlist(lapply(1:nrow(ij),function(rowId) { return
> (Powermap[i,j]<-Pr(c(ij$i[rowId],ij$j[rowId]),c(PRX,PRY),f)) }))
>
>
> as you can see lapply does not return nothing as the
> assignment is done inside the function. Would that work
> correctly? What are the cases such a statement will misfunction?
>
> I would like to thank you in advace for your help.
>
> Best Regards
> Alex
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
>



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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. Received on Wed 27 Apr 2011 - 10:24:48 GMT

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