-----Oorspronkelijk bericht-----
Van: Alaios [mailto:alaios at yahoo.com]
Verzonden: woensdag 27 april 2011 12:14
Aan: R-help at r-project.org; ONKELINX, Thierry
Onderwerp: RE: [R] Assignments inside lapply
I would like to use lapply as there is a parallel version of
lapply called mclapply.
My purpose is to convert
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 that can run in parallel with mclapply:
I am not sure then how to store the results of
lapply(mclapply) correctly to Powermap matrix. That is the
reason I put the assignment inside the return statement.
For example this does not do what I want to
Powermap[i,j]<-unlist(mclapply(1:nrow(ij),function(rowId) {
return (Pr(c(ij$i[rowId],ij$j[rowId]),c(PRX,PRY),f)
How can I try this out?
Best Regards
Alex
--- On Wed, 4/27/11, ONKELINX, Thierry
<Thierry.ONKELINX at inbo.be> wrote:
From: ONKELINX, Thierry <Thierry.ONKELINX at inbo.be>
Subject: RE: [R] Assignments inside lapply
To: "Alaios" <alaios at yahoo.com>, "R-help at r-project.org"
<R-help at r-project.org>
Date: Wednesday, April 27, 2011, 11:06 AM 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 &
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
not ensure that a reasonable answer can be extracted from a
-----Oorspronkelijk bericht-----
Van: r-help-bounces at r-project.org
[mailto:r-help-bounces at r-project.org]
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
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] <-
? ? }
}
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
done inside the function. Would that
correctly? What are the cases such a statement will
I would like to thank you in advace for your help.
Best Regards
Alex