[R] Aggregate on identical link attributes

[LCOG1]

Okay here is a solution that works in less than 60 minutes but i feel likes
its messy, if anyone has an alternative solution i would very much
appreciate your insights.  

#Create test data
TNode<-c(1:20,21)
FNode<-c(rev(1:20),22)
Volume<-c(rep(100,20),200)
ClassCode=c(rep("Local",20),rep("Freeway",1))
#Create data frame with test data
EmmeData..<-data.frame(TNode=TNode,FNode=FNode,Volume=Volume,ClassCode=ClassCode)
 
#Create vectors to establish loops
 TNodes<-unique(ED..$TNode)
 FNodes<-unique(ED..$FNode)
   
EmmeData..$TF<-paste(EmmeData..$TNode,EmmeData..$FNode,sep="-")
EmmeData..$FT<-paste(EmmeData..$FNode,EmmeData..$TNode,sep="-")
 
#Split string into 2 elements to paste back together in reverse order as a
matching ID
EmmeData..$F<-unlist(lapply(strsplit(EmmeData..$FT,split="-"), "[", 1))
EmmeData..$T<-unlist(lapply(strsplit(EmmeData..$FT,split="-"), "[", 2))
EmmeData..$Match<-paste(EmmeData..$F,EmmeData..$T,sep="-")
z<-list()
Nd<-EmmeData..$TF
for(nd in Nd){
    x<-EmmeData..[EmmeData..$TF==nd,]
    y<-EmmeData..[EmmeData..$Match==x$TF,]
    if(length(y$Volume)==0){
        z[[nd]]<-list(ID=x$TF,Volume=x$Volume,Class=x$ClassCode) 
    }
    if(length(y$Volume)==1){
        z[[nd]]<-list(ID=x$TF,Volume=x$Volume+y$Volume,Class=x$ClassCode) 
    }
    
}
 
CalcVolumes.. <- do.call('rbind', z) 


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