R help - May 2009 - readBin: read from defined offset TO defined offset?

Hello,

With the help of "seek" I can start "readBin" from any byte
offset within my
file that I deem appropriate.
What I would like to do is to be able to define the endpoint of that read as 
well. Is there any solution to that already out there?

Thanks for any hints, Joh

Can you be more specific on how you want to "define the endpoint of that
read".  What is the criteria you want to use?  Can you read in a block and
then search of the pattern?

On Mon, May 11, 2009 at 7:05 AM, Johannes Graumann
<johannes_graumann@web.de
> wrote:
> Hello,
>
> With the help of "seek" I can start "readBin" from any
byte offset within
> my
> file that I deem appropriate.
> What I would like to do is to be able to define the endpoint of that read
> as
> well. Is there any solution to that already out there?
>
> Thanks for any hints, Joh
>
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> PLEASE do read the posting guide
>
http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

	[[alternative HTML version deleted]]

On 11/05/2009 7:05 AM, Johannes Graumann wrote:
> Hello,
> 
> With the help of "seek" I can start "readBin" from any
byte offset within my
> file that I deem appropriate.
> What I would like to do is to be able to define the endpoint of that read
as
> well. Is there any solution to that already out there?
Sure:  just use the "n" parameter to readBin.  This will work for any 
type except character, but it doesn't make sense to read those in a 
given range: what do you do if the last one is not zero terminated?  If 
you want the end of block to count as a terminator, then read the block 
as raw, add a null to the end, and then re-read the raw vector.

Duncan Murdoch

Thanks guys!

Duncan's hints regarding "character" (which I was naturally using
;0) and
the double "readBin" solved my problem - I'm extracting an index
from a
REALLY big XML file to get fast direct access to subsections, so that I only 
have to parse them rather than the whole thing (only SAX-style passing would 
be possible, since there's no way the thing will fit into memory).

Thanks again, Joh

Johannes Graumann wrote:
> Hello,
> 
> With the help of "seek" I can start "readBin" from any
byte offset within
> my file that I deem appropriate.
> What I would like to do is to be able to define the endpoint of that read
> as well. Is there any solution to that already out there?
> 
> Thanks for any hints, Joh