[R] inverse table

[Marc Schwartz]

> On Jun 15, 2016, at 11:10 AM, Patrizio Frederic <frederic.patrizio at gmail.com> wrote:
> 
> Dear R-users,
> I've a problem that puzzle me
> 
> suppose I have a two way contigency  table
> 
> a <- sample(al <- letters[1:10],100,T)
> b <- sample(bl <- LETTERS[1:5],100,T)
> ab <- cbind(a,b)
> 
> ddd <- (xtabs(data = ab))
> ddd <- as.matrix(ddd)
> 
> the question is: how do I reverse the code, thus how do I get raw data
> (object ab) from ddd?
> 
> I've tried
> 
> as.data.frame.table(ddd)
> 
> which is not the answer I'm looking for.
> Thanks in advance,
> 
> PF


Hi,

There is a function called expand.dft(), which I posted some years ago, which is a modification of a prior version, posted a few years before that.

The updated version is here:

  https://stat.ethz.ch/pipermail/r-help/2009-January/378521.html

If memory serves, that code has made its way into one or more packages on CRAN but I don't recall which at the moment.

Regards,

Marc Schwartz