optimising a loop
try this:
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
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)
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)
# do matrix addressing by converting names to numbers indx <- rbind(
+ cbind(match(rownames(voisin), rownames(poids2)) + , match(voisin[, 1], colnames(poids2)) + ) + , cbind(match(rownames(voisin), rownames(poids2)) + , match(voisin[, 2], colnames(poids2)) + ) + )
indx
[,1] [,2] [1,] 1 2 [2,] 2 4 [3,] 3 2 [4,] 4 6 [5,] 5 4 [6,] 6 2 [7,] 1 5 [8,] 2 1 [9,] 3 4 [10,] 4 5 [11,] 5 1 [12,] 6 4
# change the data poids2[indx] <- c(wei2[,1], wei2[,2]) poids2
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
On Thu, Nov 3, 2011 at 1:25 PM,
<Bastien.Ferland-Raymond at mrnf.gouv.qc.ca> wrote:
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 sp?ciaux Direction des inventaires forestiers Minist?re des Ressources naturelles et de la Faune du Qu?bec
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