[R] From nested loop to mclapply

Allan Engelhardt allane at cybaea.com
Mon Apr 18 18:36:16 CEST 2011

Try help("expand.grid", package="base") for one way to create the 
combinations of (i,j) outside the loop, or perhaps vignette("nested", 
package="foreach") which does it "automatically" (rather: naturally).


On 18/04/11 16:53, Alaios wrote:
> Dear all,
> I am trying to find a decent way to speed up my code.
> So far I have used mclapply with really good results (parallel version of lapply). I have a nested loop that I would like to help me convert it to lapply
> for (i in seq(from=-1,to=1-2/ncol(sr),length=ncol(sr))){
> 	  for (j in seq(from=-1,to=1-2/nrow(sr),length=nrow(sr))){
> 	    estimatedsr[findCoord(c(i,j),sr)[1],findCoord(c(i,j),sr)[2]  ]<-fxy(c(i,j))
> 	  }
> So far I have converted some one-depth for loops to lapply but I am not sure If I can use lapply to convert a nested loop to something simpler.
> Best Regards
> Alex
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