R devel - Oct 2008 - row.names(data.frame(matrixWithDimnames)) depends on first rowname being "" or not. (PR#13230)

Full_Name: Bill Dunlap
Version: R version 2.9.0 Under development (unstable) (2008-10-29 r46795) 
OS: Linux
Submission from: (NULL) (76.28.245.14)


When data.frame() is given a matrix with rownames, then the type of the output
row names depends on whether the first element of the input row names is
"" or
not.   The other elements of the input row names don't affect things.  E.g.,
> data.frame(matrix(1:6, nrow=3, ncol=2,
dimnames=list(c("","Row 2","Row 3"),
paste("Col",1:2))))
  Col.1 Col.2
1     1     4
2     2     5
3     3     6
> data.frame(matrix(1:6, nrow=3, ncol=2, dimnames=list(c("Row
1","","Row 3"),
paste("Col",1:2))))
      Col.1 Col.2
Row 1     1     4
          2     5
Row 3     3     6

I noticed this when converting a table of word counts (by speaker) into a
data.frame and the word "" came first in the collating sequence so the
words did
not become the row names of the output.  If the "" was not first in
the table
then the row names of the input were carried into the output.

I haven't had the time yet to make a fix for this, but the distinction
between
row.names[1] != or == "" comes from code in data.frame() itself (not
as.data.frame.matrix):

     81         if (missing(row.names) && nrows[i] > 0L) {
     82             rowsi <- attr(xi, "row.names")
     83             if (!(rowsi[[1L]] %in% ""))
     84                 row.names <- data.row.names(row.names, rowsi,
     85                   i)
     86         }

Why is that check there?

Bill Dunlap
TIBCO Spotfire
wdunlap tibco.com

On Thu, 30 Oct 2008, wdunlap at tibco.com wrote:
> Full_Name: Bill Dunlap
> Version: R version 2.9.0 Under development (unstable) (2008-10-29 r46795)
> OS: Linux
> Submission from: (NULL) (76.28.245.14)
>
>
> When data.frame() is given a matrix with rownames, then the type of the
output
> row names depends on whether the first element of the input row names is
"" or
> not.   The other elements of the input row names don't affect things. 
E.g.,
>
>> data.frame(matrix(1:6, nrow=3, ncol=2,
dimnames=list(c("","Row 2","Row 3"),
> paste("Col",1:2))))
>  Col.1 Col.2
> 1     1     4
> 2     2     5
> 3     3     6
>> data.frame(matrix(1:6, nrow=3, ncol=2, dimnames=list(c("Row
1","","Row 3"),
> paste("Col",1:2))))
>      Col.1 Col.2
> Row 1     1     4
>          2     5
> Row 3     3     6
>
> I noticed this when converting a table of word counts (by speaker) into a
> data.frame and the word "" came first in the collating sequence
so the words did
> not become the row names of the output.  If the "" was not first
in the table
> then the row names of the input were carried into the output.
>
> I haven't had the time yet to make a fix for this, but the distinction
between
> row.names[1] != or == "" comes from code in data.frame() itself
(not
> as.data.frame.matrix):
>
>     81         if (missing(row.names) && nrows[i] > 0L) {
>     82             rowsi <- attr(xi, "row.names")
>     83             if (!(rowsi[[1L]] %in% ""))
>     84                 row.names <- data.row.names(row.names, rowsi,
>     85                   i)
>     86         }
>
> Why is that check there?
Well, there is a comment in the sources,

 	if(missing(row.names) && nrows[i] > 0L) {
             rowsi <- attr(xi, "row.names")
             ## old way to mark optional names
             if(!(rowsi[[1L]] %in% ""))
                 row.names <- data.row.names(row.names, rowsi, i)
         }

which was last changed in Dec 2006.  However, the behaviour was much 
older.

It seems we can now change it to just test for some non-empty row name.
>
> Bill Dunlap
> TIBCO Spotfire
> wdunlap tibco.com
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595