[R] long algo

[william ritchie]

Hi everyone,

 I ve been using R for months and find it really
practical and straight forward.
However (the inevitable however), I am finding it very
slow for one of my operations:
it s basically an itertation over i and j in a pretty
big table (4* 4608). It takes 30 minutes!!!!

Thanks


Ps:if it can help here is the source:

median1<-matrix(nrow=4608,ncol=1)
median2<-matrix(nrow=4608,ncol=1)
median3<-matrix(nrow=4608,ncol=1)
median4<-matrix(nrow=4608,ncol=1)
v<-c(18,19,20,21,23)
for (i in 0:11)
    {
     for (j in 1:384)
        {    
         
median1[j+(i*384),]<-puce[j+(i*384),5]+median(puce[v+384*i,2]-puce[v+384*i,5])
        
median2[j+(i*384),]<-puce[j+(i*384),19]+median(puce[v+384*i,16]-puce[v+384*i,19])
        
median3[j+(i*384),]<-puce[j+(i*384),12]+median(puce[v+384*i,9]-puce[v+384*i,12])
        
median4[j+(i*384),]<-puce[j+(i*384),26]+median(puce[v+384*i,23]-puce[v+384*i,26])
         
       
          puce[,5]<-median1
         puce[,19]<-median2
         puce[,12]<-median3
         puce[,26]<-median4


         }
     }