GNU Data Language (GDL) - a free and open-source implementation of IDL
RSylwester Arabas
1, Marc Schellens
*, Alain Coulais
2, Joel Gales
3, Peter Messmer
4, and many other volunteers all around the world
***: Marc is the primary author and the maintainer of GDL **: a list of contributors is available at the project’s website (http://gnudatalanguage.sf.net/) and in the AUTHORS file of the GDL tarballs and packages
1: Institute of Geophysics, University of Warsaw, Poland; 2: LERMA, CNRS and Observatoire de Paris, Paris, France; 3: NASA Goddard Space Flight Center, Greenbelt, Maryland, USA; 4: Tech-X Corporation, Boulder, Colorado, USA
About GDL
GNU Data Language (GDL) is developed with the aim of providing
an open-source drop-in replacement for the ITTVIS’s Interactive Data Language (IDL). It is free software developed by an international team of volunteers led by Marc Schellens - the project’s founder (a list
of contributors is available on the project’s website). GDL with its library routines is designed as a tool for numerical data analysis and
visualisation. As its proprietary counterparts (IDL and PV-WAVE), GDL is used particularly in geosciences and astronomy. GDL is
dynamically-typed, vectorized and has object-oriented programming capabilities. The library routines handle numerical calculations, data
visualisation, signal/image processing, interaction with host OS and data input/output. GDL supports several data formats such as netCDF,
HDF4, HDF5, GRIB, PNG, TIFF, DICOM, etc. Graphical output
is handled by X11, PostScript, SVG or z-buffer terminals, the last one
allowing output to be saved in a variety of raster graphics formats. While still being in its beta-stage of development (see Coulais et al., 2009),
GDL proved to be a usable tool both for research (Jaffey et al., 2008, 2009) and teaching purposes (outlined hereby). GDL is released under the GNU GPL licence - you are free to use it, to share it with anyone,
to modify and improve it, and to share the modified version with anyone.
Contributions and users’ feedback are welcome!
References
Coulais, A., M. Schellens, J. Gales, S. Arabas, M. Boquien, P. Chanial, P. Messmer, D. Fillmore, O. Poplawski, S. Maret, G. Marchal, N. Galmiche, and T. Mermet, 2009:
Status of GDL - GNU Data Language. Astronomical Data Analysis Software and Systems XIX , ASP Conference Series, Sapporo, Japan.
http://aramis2.obspm.fr/coulais/.
Jaffey, A., M. Cheung, and A. Kobashi, 2008: Online data analysis using Web GDL.
AGU Fall Meeting 2008, San Francisco, USA. http://www.agu.org/meetings/fm08/.
Jaffey, A., A. Kobashi, and M. Cheung, 2009: GPU acceleration of the scientific data analysis package GDL. NVIDIA Research Summit 2009, San Jose, USA.
http://www.nvidia.com/object/gtc 2009 archive.html.
Acknowledgements
Presentation of the poster during the EGU conference in Vienna was supported by the European Geosciences Union (through the Young Scientist’s Travel Award for
Europeans) and the European Commission’s 6th FP IP EUCAARI (European Integrated project on Aerosol Cloud Climate and Air Quality interactions, no. 036833-2). Thanks are due all volunteers who helped in the development of GDL by providing their feedback in the form of patches, bug reports, support requests and comments. Development of GDL is hosted at SourceForge. The LIDAR figure was provided by Michał Piądłowski.
Disclaimer
GDL is not an official GNU package (yet). IDL is a registered trademark of ITT Visual Information Solutions (http://www.ittvis.com/).
Dependencies and useful libraries (all free & open)
GDL is an incremental compiler with integrated debugging facilities. It is written in C++ using the ANTLR language-recognition framework. Extensions to GDL can be written in C++, GDL, and
Python. Most of the library routines are implemented as interfaces to open-source libraries:
GNU
Scientific Library
(GSL)
Terence Parr's
ANTLR
C++
STL, GCC
OpenMP
(GCC >4.2) UNIDATA's
netCDF
HDFGroup's
HDF4
ECMWF's
GRIB API
HDFGroup's
HDF5
Image Magick's
Magick++
Robbie Barnett's
GDLffDICOM
free, open & libre:
free & open:
MIT's
FFTW
Python Python
wxWidgets
Paul Wessel's
GSHHS
PLplot
Gerald I.
Evenden's
libproj4
UNIDATA's
UDUNITS
Matthew Craig's
TeXtoIDL
(optional) (mandatory)
readline zlib
...
GNU
autotools
(for development only)
Craig
Markwardt's
MPFIT
curve fitting, function minimi-
zation
2D & 3D plots,
contours, surfaces, text annotations
etc
NASA's
Astron lib
incl. FITS IO
Craig
Markwardt's
CMSVLIB
IDL's SAVE files I/O
calling Python code from GDL &
GDL as a Python module
shorelines etc
simple linear algebra, random numbers, histograms, interpolation,
splines, root-finding, physical constants catalogue, wavelets,
etc
(optional)
(IDL-written libraries functional under GDL)
e.g.
multithreaded matrix
op.
grammar description parsers
Example usage of GDL for classroom work on data analysis
GDL proved to be a useful tool for classroom work on data
analysis. In 2010 it was used for the second time as a data-analysis environment during a meteorological-data processing course
taught at the Institute of Geophysics, University of Warsaw. The course covers hands-on training in handling of scientific data sets.
GDL is used for reading GRIB, netCDF & HDF files, and performing basic data analysis and visualisation tasks.
GDL plotting weather-forecast map from a GRIB file with NOAA GFS model output.
GDL used for analyzing LIDAR data (reading netCDF files, producing PostScript plots) on
Linux, using the IDLWAVE mode for Emacs.
GDL used as a part of a web-interface for controlling 2D fluid flow simulation and visualizing the output (reading netCDF files
and outputting SVG plots).
GDL-generated PostScript plot of a Fourier spectrum in a LaTeX-generated PDF file.
GDL compressing weather-radar images using truncated wavelet approximation.
GDL used for demonstrating Kalman filtering on randomly-generated signal.
GDL displaying MODIS satellite image (stored in a HDF file) on multiple X11
windows - using a true-color RGB
composite, and using separate channels.
Supported platforms and availability of pre-compiled/pre-configured packages
Packaged versions of GDL are available for several Linux distributions
(incl. Fedora, Gentoo and Debian) and Mac OS X (e.g. via Macports and Fink). The source code (available at http://gnudatalanguage.sf.net/)
compiles on other UNIX systems, including BSD, OpenSolaris.
TM TMPoster presented at the European Geosciences Union General Assembly 2010, May 2010, Vienna, Austria (ESSI1 session: Earth & Space Science Informatics / International Geoscience Informatics Partnerships, Projects, and Collaboration Technologies)
