Re: [R] hex format

From: Duncan Murdoch <>
Date: Sat 09 Apr 2005 - 02:53:03 EST

Earl F. Glynn wrote:

>I recently discovered R's writeBin and readBin functions. readBin, in
>particular, looks like an extremely powerful tool for loading external
>files. This might be an easier way to perform some one-time data
>manipulations instead of writing a separate C, Perl or Delphi program to
>manipulate data before bringing it into R for analysis.
>readBin returns a "raw" data type that looks like an array of bytes that R
>displays in hex. That's where my problem begins and why I joined this "hex
>format" thread.
That's only one possibility. readBin can return a number of different types.

>I'd love to manipulate this raw hex data, but R makes using these hex bytes
>quite difficult to use (or more difficult than I think it should be based on
>how easy it is in other languages). I might want to interpret a byte, or a
>string of bytes, as characters.
A simple solution to this would be to implement a "raw connection", that takes a raw variable and lets you read it using readBin.

> Or, I might want to interpret pairs of
>bytes as 2-byte unsigned (or possibly signed) integers. Or, I might want to
>interpret 3-bytes at a time as RGB values (in either RGB or BGR order). Or,
>I might want to interpret 8-bytes at a type as a IEEE754 floating point
>Every time someone wants to manipulate this raw data in R, as far as I can
>tell now, one must start from scratch and do all sorts of manipulations on
>these hex byte values to get characters, or integers, or doubles. And
>because it's not that easy (but it's not that hard either, more of an
>annoyance), I guess many just go back to C to get that job done there and
>then return to R.
Currently you can do it by writing the raw data out to a temporary file and reading it back in. It would be nice to allow this to happen without the temporary file.

Duncan Murdoch mailing list PLEASE do read the posting guide! Received on Sat Apr 09 02:57:48 2005

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