Thanks very much, Professor Ripley.
Reid Huntsinger
-----Original Message-----
From: ripley at stats.ox.ac.uk [mailto:ripley at stats.ox.ac.uk]
Sent: Tuesday, August 06, 2002 3:00 AM
To: Huntsinger, Reid
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] pipe and binary i/o (on Linux)
On Mon, 5 Aug 2002 ripley at stats.ox.ac.uk wrote:
> pipe predates readBin, and no one has seen a reason to do this before you.
However, gzfile should work, and bzfile *always* opens with "rb".
Here's
an example on RH7.2:
> zz <- gzfile("testbin.gz", "wb")
> writeBin(1:10, zz)
> close(zz)
> zz <- gzfile("testbin.gz", "rb")
> readBin(zz, integer(), 4)
[1] 1 2 3 4> readBin(zz, integer(), 6)
[1] 5 6 7 8 9 10> close(zz)
> zz <- pipe("gzcat testbin.gz", "rb")
Error in pipe("gzcat testbin.gz", "rb") : unable to open
connection
In addition: Warning message:
cannot open cmd `gzcat testbin.gz'
so pipe has problems, as on Linux popen does not respect "rb"
(although on
other platforms it seems to).
> It's an adequate fix.
On Linux, that is: Windows needs the "b". I've put a full fix in
R-devel.
>
> On Mon, 5 Aug 2002, Huntsinger, Reid wrote:
>
> > I often want to use "pipe" with "readBin" to read
(binary) data from the
> > standard output of a Perl or C program. For that I need
"pipe" to work
with> > the "open='rb'" option. It never worked for me, and
after a look at the
> > connections.c file, I see that in "pipe_open" the mode gets
passed
directly> > to "popen" (I'm using Linux on an Intel machine). Popen
doesn't know
"rb"> > and fails. I modified the pipe function in connection.c to pass only
the
> > first character of the mode. This seems to work (fingers crossed).
Then
I> > noticed gzfile has the same problem, but bzfile doesn't, and uses
the
same> > solution as I did for pipe. Can I assume that this is a correct fix?
Or
were> > there reasons that pipe and gzfile wouldn't allow "rb"?
> >
> > Thanks,
> >
> > Reid Huntsinger
>
> [irrelevant message deleted]
>
> --
> 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 272860 (secr)
> Oxford OX1 3TG, UK Fax: +44 1865 272595
>
>
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--
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 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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