Working with GWOSC Data Using C
C developers have at least two options for libraries that will
read GWOSC data files - the Frame Library and HDF5. If
you have no strong reason
to prefer C, you may find the python-based instructions in the
Introductory Tutorial a quicker way to
get started.
The Frame Library
GWOSC data files in the gravitational wave frame file
format (.gwf) may be read using the
Frame Library.
HDF5
GWOSC data files in the HDF5 file
format (.hdf5) may be read using the
HDF5 Library.
The
HDF5 in C example script
is a minimal example, showing how to
extract the most essential data from a GWOSC data file.
More complete documentation on HDF5 is
available on the
HDF Group web site.
In the GWOSC computing enviornment, the example script may be compiled
with this command:
gcc -o hdf5_losc hdf5_losc.c -lhdf5 -D H5_USE_16_API
On a mac, macports may be used to install HDF5, in which case the
example script may be compiled with a command similar to this:
gcc -o hdf5_losc hdf5_losc.c -lhdf5 -D H5_USE_16_API -I /opt/local/include -L/opt/local/lib
All computing envoirnments are a little different, so compiling on your
computer may not work in exactly the same way.
Running the example script should produce output similar to this:
$ ./hdf5_losc
/quality/simple/DQmask:
[ 196591 196591 196591 196591 196591 196591 196591 196591 196591 196591 ... ]
The total live time for this 4096 s file is: 3481 seconds
/strain/Strain:
[ 8.302311e-17 9.192293e-17 1.007950e-16 1.095800e-16 1.182704e-16
1.269312e-16 1.354517e-16 1.439318e-16 1.522801e-16 1.605206e-16 ... ]
GWOSC Data File Structure
For an overview of the GWOSC data file structure, see the
Introduction to GWOSC Data Files tutorial. In
addition, both the HDF5 Library and the Frame Library provide tools
for reading or "dumping" the structure of a file. For example,
HDFView
provides a GUI interface to HDF5 files. If working with
GWF files, the
FrDump is a quick way to see
what information is available in a frame file.
