x<-c('A','B','C')
data<-expand.grid(x,x)
data$value<-c(1,2,3,2,1,4,3,4,1)
r.data<-reshape(data, idvar = "Var1", timevar = "Var2", direction = "wide")
colnames(r.data)<-c('Var','A','B','C')
rownames(r.data)<-r.data$Var
r.data$Var<-NULL

get_lower_tri<-function(cormat){
  cormat[upper.tri(cormat)] <- NA
  return(cormat)
}
r.data_lower<-get_lower_tri(r.data)