Hello,
I needed a function like table(), but which used the value of a column
instead of counting occurences, but could not find anything in the
builtin modules (maybe I missed it...). SO I decided to write my own, and
I came up with the following:
table.ponderate<-function(arow,acol,aweight){
matrix(data=0,nrow=length(levels(arow)),ncol=length(levels(acol)),
byrow=TRUE,dimnames=list(levels(arow),levels(acol)))->m
aweight[is.na(aweight)]<- 0
for (a in seq(length(arow))) {
prev<-m[as.integer(arow[a]),as.integer(acol[a])]
m[as.integer(arow[a]),as.integer(acol[a])]<-prev+aweight[a]
}
m
}
The problem is that the performance is very poor. I have not had time to
benchmark it, but it takes several seconds to process 1000 lines, and I
need to process a few dozens of 10000+ lines data sets.
Is there a way to write things differently that could speed up things?
Alexandre Fayolle
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