From rpeng at jhsph.edu  Wed Dec 21 23:13:54 2005
From: rpeng at jhsph.edu (Roger D. Peng)
Date: Wed, 21 Dec 2005 17:13:54 -0500
Subject: [Rd] random output with sub(fixed = TRUE)
In-Reply-To: <x23bkmun5v.fsf@turmalin.kubism.ku.dk>
References: <43A9CB12.1020803@jhsph.edu> <x23bkmun5v.fsf@turmalin.kubism.ku.dk>
Message-ID: <43A9D3A2.6040103@jhsph.edu>

Well, who am I to break this long-standing ritual? :)

Interestingly, while the printed output looks wrong, I get

 > v <- paste(0:10, "asdf", sep = ".")
 > a <- sub(".asdf", "", v, fixed = TRUE)
 > b <- as.character(0:10)
 > identical(a, b)
[1] TRUE
 >

-roger

Peter Dalgaard wrote:
> "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...
> 

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



[Rd] random output with sub(fixed = TRUE)
Roger D. Peng