[R] reading binary file

Martin Maechler maechler at stat.math.ethz.ch
Mon Oct 18 15:19:46 CEST 1999

>>>>> "Yudi" == Yudi Pawitan <yudi at ucd.ie> writes:

    Yudi> Is there facility in R to read binary file? In Splus scan() has
    Yudi> 'width=' argument and AsciiToInt() command to translate the
    Yudi> binary data. Is there something similar in R?

hmm, two things  ---rather thoughts than proposals---

- ASCII is 7bit, binary is 8bit;
  but indeed: S-plus' AsciiToInt(ch) [formerly known as  ichar()] 
  works for 8bit strings as well.
- in R, we allow for ``8bit extended ASCII'' (actually iso-latin-1) 
  which enables us non-English speakers (and writers) to use our language
  "accents", and, using using 'locale's even to sort accordingly.

  The drawback of our `localized' approach is that  AsciiToInt() 
  ---if we'd implement it--- would be localized as well
  {but then scan(what="") would be too, and then reading binary, using this
   hack should work, locale-independently...}.

Maybe a better approach would be to directly read binary bytes into
integers, 2 or 4 bytes into one integer 
(R requires C integers with at least 32 bits).

The two simple function  pack8bit() and unpack8bit()  which are now part of
the wavethresh package on CRAN {{and are applied to store the
	       		        picture of John Lennon more efficiently}}
could come handy here.

Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO D10	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><
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