[R] inverse table

Patrizio Frederic
Thu, 16 Jun 2016 09:10:46 -0000

Thank you all,
David's solution is the one that matches my taste the most.

Patrizio

On Wed, Jun 15, 2016 at 8:04 PM, David L Carlson <dcarlson at tamu.edu>
wrote:

> After converting the table to a data frame, replicate each row by the
> number of observations:
>
> > ddd.df <- as.data.frame(ddd)  # as.data.frame.table does the same
thing
> > ddd.new <- as.matrix(ddd.df[rep(seq_along(ddd.df[, 1]),
ddd.df$Freq),
> 1:2])
> > head(ddd.new)
>     a   b
> 1   "a" "A"
> 1.1 "a" "A"
> 2   "b" "A"
> 2.1 "b" "A"
> 3   "c" "A"
> 4   "d" "A"
> > rownames(ddd.new) <- NULL # Optional - get rid of row names
> > head(ddd.new)
>      a   b
> [1,] "a" "A"
> [2,] "a" "A"
> [3,] "b" "A"
> [4,] "b" "A"
> [5,] "c" "A"
> [6,] "d" "A"
>
> -------------------------------------
> David L Carlson
> Department of Anthropology
> Texas A&M University
> College Station, TX 77840-4352
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Patrizio
> Frederic
> Sent: Wednesday, June 15, 2016 11:10 AM
> To: r-help at r-project.org
> Subject: [R] inverse table
>
> 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
>
>
>
> --
> +---------------------------------------------------------------
> | Patrizio Frederic,
> | http://morgana.unimore.it/frederic_patrizio/
> +---------------------------------------------------------------
>
>         [[alternative HTML version deleted]]
>
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--
+---------------------------------------------------------------
| Patrizio Frederic,
| http://morgana.unimore.it/frederic_patrizio/
+---------------------------------------------------------------