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
number.
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
______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
