R devel - Jul 2013 - duplicated.data.frame() is broken on data frames containing \r

Hi,

The trick used by duplicated.data.frame() is to transform the supplied
data.frame into a character vector by pasting together the columns using
"\r" as separator. But no precautions are taken to deal with
"\r" in
the supplied data.frame. As a consequence it's easy to imagine
situations where duplicated.data.frame() returns an incorrect answer:

   > df <- data.frame(a=c("AA", "AA\r"),
b=c("\rBBB", "BBB"))
   > df
        a     b
   1   AA \rBBB
   2 AA\r   BBB
   > duplicated(df)
   [1] FALSE  TRUE

Cheers,
H.

 > sessionInfo()
R version 3.0.1 (2013-05-16)
Platform: x86_64-unknown-linux-gnu (64-bit)

locale:
  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
  [7] LC_PAPER=C                 LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base


-- 
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fhcrc.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319

OK it's actually documented:

      The data frame method works by pasting together a character
      representation of the rows separated by ?\r?, so may be imperfect
      if the data frame has characters with embedded carriage returns or
      columns which do not reliably map to characters.

But what about fixing it? One possible fix is to use "\r\r" as
separator and to substitute user-supplied "\r" with, say,
"#\r#".
Just an example.

Thanks,
H.


On 07/29/2013 11:52 AM, Herv? Pag?s wrote:
> Hi,
>
> The trick used by duplicated.data.frame() is to transform the supplied
> data.frame into a character vector by pasting together the columns using
> "\r" as separator. But no precautions are taken to deal with
"\r" in
> the supplied data.frame. As a consequence it's easy to imagine
> situations where duplicated.data.frame() returns an incorrect answer:
>
>    > df <- data.frame(a=c("AA", "AA\r"),
b=c("\rBBB", "BBB"))
>    > df
>         a     b
>    1   AA \rBBB
>    2 AA\r   BBB
>    > duplicated(df)
>    [1] FALSE  TRUE
>
> Cheers,
> H.
>
>  > sessionInfo()
> R version 3.0.1 (2013-05-16)
> Platform: x86_64-unknown-linux-gnu (64-bit)
>
> locale:
>   [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>   [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
>   [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
>   [7] LC_PAPER=C                 LC_NAME=C
>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
>
-- 
Herv? Pag?s

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fhcrc.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319