[R] Help for looping

[Adaikalavan Ramasamy]

Please try to give a simple reproducible example and simplify your codes 
a bit if you want to get useful responses.

For example, you say your data is a matrix of 1000*30, where I presume 
the matrix has 1000 rows and 30 columns. If so EMP <- data[,378:392] 
does not make sense.

Perhaps you might be interested in knn() in the class package.

Regards, Adai




tkobayas at indiana.edu wrote:
> Rusers:
> 
> I have tried to minimize computing times by taking advanage of 
> lapply(). My data is a 1000*30 matrix and the distance matrix was 
> created with dist(). What I am trying to do is to compute the standard 
> distances using the frequencies attached to the nearest negibors of n 
> reference zones. So I will have 1000 standard distances, and would like 
> to see the frequency distribution of the standard distances.
> 
> # Convert decimal degrees into UTM miles
> x<-(data[,1]-58277.194363)*0.000621
> y<-(data[,2]-4414486.03135)*0.000621
> 
> # Combine x y for computing distances
> coords<-cbind(x,y)
> pts<-length(data)
> 
> # Subset housing data and employment data
> RES<-data[,3:17]
> EMP<-data[,378:392]
> 
> # Combine all the subdata as D
> D<-cbind(coords,RES,EMP)
> 
> cases<-ncol(D)-ncol(coords)
> 
> # Create a threshold bandwidth for defining the nearest neighbors
> thrs<-seq(0,35,by=1)
> 
> SDTAZ<-rep(list(matrix(,nrow(D),length(thrs))),cases)
> 
> 
> for (j in 1:nrow(D))
> for (k in 1:length(thrs))
> for (l in 1:cases)
> {
> {
> {
> 
> SDTAZ[[l]][j,k]<-
> sqrt(
>    sum(
> 	(D[as.vector(which(dis[j,]<=thrs[k])),l+2]-D[j,l+2]-
>           min(D[as.vector(which(dis[j,]<=thrs[k])),l+2]-D[j,l+2])+1)*
>          (
> 	   (dis[j,as.vector(which(dis[j,]<=thrs[k]))])^2
>          )
>       )
> 
> 	/sum(D[as.vector(which(dis[j,]<=thrs[k])),l+2]-D[j,l+2]-
>          min(D[as.vector(which(dis[j,]<=thrs[k])),l+2]-D[j,l+2])+1)
> 		)
> }
> }
> }
> 
> I think that within this nested loop, I should use lapply() but I ended 
> up getting different values.... I appreciate if someone could kindly 
> help me.
> 
> Thank you very much.
> ------------------------------------
> Takatsugu Kobayashi
> PhD Candidate
> Indiana University, Dept. Geography
> 
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