Skip to content

Fortran ACCESS='DIRECT' for importing Binary Files

2 messages · Jared Stabach, Dirk Eddelbuettel

Original
Jared Stabach
# 
Is there a command similar to Fortran's Access='DIRECT' command for reading
binary files in R?  I am interested in writing a program to access specific
parts of a binary file, where many years of results are bound together in
one file.

An option would be to call this Fortran function from within R.

Thanks for any thoughts.

Jared
Dirk Eddelbuettel
#
On 16 April 2014 at 14:58, Jared Stabach wrote:
| Is there a command similar to Fortran's Access='DIRECT' command for reading
| binary files in R?  I am interested in writing a program to access specific
| parts of a binary file, where many years of results are bound together in
| one file.

I have no idea what 

  Fortran's Access='DIRECT'

is or does, and suspect this question belongs onto r-devel instead .

That said, I may have devised such a simple binary file format for our use at
work where we frequently need to read large matrices (and typically less
frequently write them in batch jobs).

So I write out a header with a few fixed ints about dimension and type, and
then just have one large read of rows * cols elements of size double.  And
the nice thing about R is that you can do all of this in R code (!!) via

    gzfile()            to open a compressed file
    readBin()           to read int or double

so no need to go to C or Fortran.  See the docs on help(connection) and
help(readBin).   (And yes, the format is accessible from C/C++ or other
languages such as Python too provided they can read binary blobs from gzip'ed
file)

Dirk