[R] Transforming relational data

[mathijsdevaan]

OK, for the last step I have tried this (among other things): 
library(data.table) 
DT = data.table(read.table(textConnection("    A  B  C 
1 1  a  1999 
2 1  b  1999 
3 1  c  1999 
4 1  d  1999 
5 2  c  2001 
6 2  d  2001
7 3  a  2004
8 3  b  2004
9 3  d  2004"),head=TRUE,stringsAsFactors=FALSE)) 

firststep = DT[,cbind(expand.grid(B,B),v=1/length(B)),by=C][Var1!=Var2] 
setkey(firststep,Var1,Var2) 
list1<-firststep[J(expand.grid(DT$B,DT$B),v=1/length(DT$B)),nomatch=0][,sum(v)]
list1
#27

What I would like to get:
list
1  0
2  0.5
3  2.5

Thanks!
-- 
View this message in context: http://r.789695.n4.nabble.com/Re-Transforming-relational-data-tp3307449p3312140.html
Sent from the R help mailing list archive at Nabble.com.