R devel - Dec 2005 - random output with sub(fixed = TRUE)

I've noticed what I think is curious behavior in using 'sub(fixed =
TRUE)' and
was wondering if my expectation is incorrect.  Here is one example:

v <- paste(0:10, "asdf", sep = ".")
sub(".asdf", "", v, fixed = TRUE)

The results I get are

 > sub(".asdf", "", v, fixed = TRUE)
  [1] "0"               "1\0st\0\0"      
"2\0<af>\001\0\0" "3\0<af>\001\0\0"
  [5] "4\0mes\0"        "5\0<ba>\001\0\0"
"6\0\0\0\0\0"     "7\0\0\0m\0"
  [9] "8\0\0\0t\0"      "9\0<fe>\0\0\0"  
"10\0\0\0\0\0"
 >

I expected "0" in the first entry and everything else would be
unchanged.  Your
results may vary since every time I run 'sub()' in this way, I get a
slightly
different answer in entires 2 through 11.

As it turns out, 'gsub(fixed = TRUE)' gives me the answer I *actually*
wanted,
which was to replace the string in every entry.  But I still think the behavior 
of 'sub(fixed = TRUE) is a bit odd.

 > version
          _
platform x86_64-unknown-linux-gnu
arch     x86_64
os       linux-gnu
system   x86_64, linux-gnu
status
major    2
minor    2.1
year     2005
month    12
day      20
svn rev  36812
language R
 >

-roger
-- 
Roger D. Peng  |  http://www.biostat.jhsph.edu/~rpeng/

"Roger D. Peng" <rpeng at jhsph.edu> writes:
> I've noticed what I think is curious behavior in using 'sub(fixed =
TRUE)' and
> was wondering if my expectation is incorrect.  Here is one example:
> 
> v <- paste(0:10, "asdf", sep = ".")
> sub(".asdf", "", v, fixed = TRUE)
> 
> The results I get are
> 
>  > sub(".asdf", "", v, fixed = TRUE)
>   [1] "0"               "1\0st\0\0"      
"2\0<af>\001\0\0" "3\0<af>\001\0\0"
>   [5] "4\0mes\0"        "5\0<ba>\001\0\0"
"6\0\0\0\0\0"     "7\0\0\0m\0"
>   [9] "8\0\0\0t\0"      "9\0<fe>\0\0\0"  
"10\0\0\0\0\0"
>  >
> 
> I expected "0" in the first entry and everything else would be
unchanged.  Your
> results may vary since every time I run 'sub()' in this way, I get
a slightly
> different answer in entires 2 through 11.
> 
> As it turns out, 'gsub(fixed = TRUE)' gives me the answer I
*actually* wanted,
> which was to replace the string in every entry.  But I still think the
behavior
> of 'sub(fixed = TRUE) is a bit odd.
> 
>  > version
>           _
> platform x86_64-unknown-linux-gnu
> arch     x86_64
> os       linux-gnu
> system   x86_64, linux-gnu
> status
> major    2
> minor    2.1
> year     2005
> month    12
> day      20
> svn rev  36812
> language R
>  >
Argh... 

year     2005
month    12
day      21

and something like this gets discovered. It's a ritual, I tell ya, a ritual!

If you look at the output and terminate all strings at the embedded
\0, it looks much more sensible, so it should be fairly easy to spot
the cause of this bug...

-- 
   O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907