Try replacing your for loop with the line loop[cbind(as.vector(row(voisin)), match(voisin, nom.plac2))] <- as.vector(wei2)
Look help(Subscript) to see how subscripting an n-way array by an n-column integer matrix works. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Bastien.Ferland- > [email protected] > Sent: Thursday, November 03, 2011 10:25 AM > To: [email protected] > Subject: [R] optimising a loop > > Dear R community, > > I'm trying to remove a loop from my code but I'm stock and I can't find a > good way to do it. > Hopefully one of you will have something clever to propose. > > Here is a simplified example: > > I have a squared matrix: > > > nom.plac2 <- c("102", "103", "301", "303","304", "403") > > poids2 <- matrix(NA, 6,6, dimnames=list(nom.plac2,nom.plac2)) > > poids2 > 102 103 301 303 304 403 > 102 NA NA NA NA NA NA > 103 NA NA NA NA NA NA > 301 NA NA NA NA NA NA > 303 NA NA NA NA NA NA > 304 NA NA NA NA NA NA > 403 NA NA NA NA NA NA > > I want to replace some of the NAs following specific criterion included in 2 > others matrix: > > > wei2 <- > > matrix(c(.6,.4,.5,.5,.9,.1,.8,.2,.7,.3,.6,.4),6,2,dimnames=list(nom.plac2, > c("p1","p2")),byrow=T) > > wei2 > p1 p2 > 102 0.6 0.4 > 103 0.5 0.5 > 301 0.9 0.1 > 303 0.8 0.2 > 304 0.7 0.3 > 403 0.6 0.4 > > voisin <- matrix(c("103","304", "303", "102", "103" > > ,"303","403","304","303","102","103" ,"303"), > 6,2,dimnames=list(nom.plac2, c("v1","v2")),byrow=T) > > voisin > v1 v2 > 102 "103" "304" > 103 "303" "102" > 301 "103" "303" > 303 "403" "304" > 304 "303" "102" > 403 "103" "303" > > So my final result is: > > 102 103 301 303 304 403 > 102 NA 0.6 NA NA 0.4 NA > 103 0.5 NA NA 0.5 NA NA > 301 NA 0.9 NA 0.1 NA NA > 303 NA NA NA NA 0.2 0.8 > 304 0.3 NA NA 0.7 NA NA > 403 NA 0.6 NA 0.4 NA NA > > > So, globally I want to fill for each line of "poids2" data from "wei2" > associated with the good the > good identifier found in "voisin". > > This can easily be done by a loop: > > > loop <- poids2 > > for(i in 1:6){ > + loop[i,voisin[i,]] <- wei2[i,] > + } > > But I expect it to be quite slow with my larger dataset. > > Does any of you has an idea how I could remove the loop and speed up the > operation? > > Best regards, > > > Bastien Ferland-Raymond, M.Sc. Stat., M.Sc. Biol. > Division des orientations et projets spéciaux > Direction des inventaires forestiers > Ministère des Ressources naturelles et de la Faune du Québec > > ______________________________________________ > [email protected] 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. ______________________________________________ [email protected] 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.
