R help - Jun 2011 - Obtaining OLAP cubes using R

Hello All,

I have a dataset and I wish to obtain all possible data cuboids from it 
using R . For eg if my data frame is :

A    B    C
1    1    1
1    2    1
2    2    1

The output intended is :
A=1
A=2
B=1
B=2
C=1
A=1,B=1
A=1,B=2
A=2,B=2
A=1,C=1
A=2,C=1
B=1,C=1
B=2,C=1
A=1,B=1,C=1
A=1,B=2,C=1
A=2,B=2,C=1

Are there any function(s) to do this in R ? I tried a combination of 
expand.grid and combn but the resulting code was very ugly and needed 
lot of hacks to make it work. I also tried to check the code for arules 
(which constructs similar "itemsets") but unfortunately its code is in
C
and I am not very familiar in writing R extensions. Any pointers to 
functions will be much appreciated.

Regards,
Saravanan

Ho Saravana,

I did have nearly the same issue some months ago -- you will find below a
good starting point.
I am quite sure there is a better way to achieve it or with better code,
but this should work!

Kind regards,

Eric


---------
generateCube <- function(x,simplify=TRUE,onlyComb=FALSE,...){
stopifnot(require(gtools))
xdf=as.data.frame(x)
out=vector(length=ncol(xdf),mode="list")
for (i in 1:ncol(xdf)){ # dimensions of the cube
 icomb <- combinations(length(colnames(xdf)),i,colnames(xdf))
 out[[i]] <- vector(length=nrow(icomb),mode="list")
 for (j in 1:nrow(icomb)){
  ijargs <- icomb[j,]
  names(out[[i]])[j] <- paste(ijargs,collapse="*")
  tmp <-
   with(
   xdf,
   eval(parse(text   
paste("table(",paste(ijargs,collapse=","),")",sep="")
    ))
  )
  if (simplify & i>1) tmp<-as.data.frame(ftable(tmp))
  out[[i]][[j]] <- tmp
  }
 }
return(out)
}
M=diag(3)
M[1,2]=2
M <- rbind(M,M[1,])
colnames(M) <- paste("V",1:ncol(M),sep="")
out=generateCube(M)
out2=generateCube(M,simplify=FALSE)

out[[2]][["V1*V3"]]
out2[[2]][["V1*V3"]]["0","1"]
-------------




On 14 June 2011 14:59, Saravanan
<saravanan.thirumuruganathan@gmail.com>wrote:
> Hello All,
>
> I have a dataset and I wish to obtain all possible data cuboids from it
> using R . For eg if my data frame is :
>
> A    B    C
> 1    1    1
> 1    2    1
> 2    2    1
>
> The output intended is :
> A=1
> A=2
> B=1
> B=2
> C=1
> A=1,B=1
> A=1,B=2
> A=2,B=2
> A=1,C=1
> A=2,C=1
> B=1,C=1
> B=2,C=1
> A=1,B=1,C=1
> A=1,B=2,C=1
> A=2,B=2,C=1
>
> Are there any function(s) to do this in R ? I tried a combination of
> expand.grid and combn but the resulting code was very ugly and needed lot
of
> hacks to make it work. I also tried to check the code for arules (which
> constructs similar "itemsets") but unfortunately its code is in C
and I am
> not very familiar in writing R extensions. Any pointers to functions will
be
> much appreciated.
>
> Regards,
> Saravanan
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
>
http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Eric Lecoutre
Consultant - Business & Decision
Business Intelligence & Customer Intelligence

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