user defined functions with varying z or t... does it work in grads2.0?

[Arlindo da Silva]

On Fri, Feb 29, 2008 at 10:08 AM, Henrique Barbosa <hmjbarbosa at gmail.com>
wrote:

> Dear all,
>
> User defined functions in grads are an extremely useful and
> powerfull feature. However, I never managed to use it with data
> varying in either z or t coordinates, even though the user manual
> says it should work. Apparently, this possibility is not implemented
> (at least that's what I understood from previous messages).
>
> Since new grads is out, I wonder if this issue is fixed. Can anyone
> tell if grads2.0 allows user defined functions with varying z or t?
> If not, what are the plans to implement that?
>
> I nice application would be to do a time fourier transform.
> I haven't figured out how to do that from grads without UDF...
>
>
For precisely reasons like yours that I ended up  writing PyGrADS (Python
interface to GrADS). There, you can easily extract a  2D, 3D or 4D arrays
from GrADS, and do your  Fourier analysis (and whole lot more) using  PyLab
and SciPy, Python packages that implement among other things, very robust
digital signal processing functions, with a high degree of Matlab(tm)
compatibility. The downside is that you would need to learn python (assuming
don't already know it), and install PyGrADS and its dependencies, most of
which are available in recent Linux distributions, Windows and Mac OS X. At
this point only GrADS v1.9.0-rc1 is fully supported by PyGrADS, although it
is our intention to have it working with GrADS v2 whenever dynamic
extensions are enabled there. (At this point only the core functionality of
PyGrADS works with GrADS v2.) You can find more information some of these
topics at the links below.

     http://opengrads.org/wiki/index.php?title=Python_Interface_to_GrADS
     http://matplotlib.sourceforge.net/pylab_commands.html
     http://matplotlib.sourceforge.net/users_guide_0.91.2svn.pdf
     http://www.scipy.org/

         Arlindo

--
Arlindo da Silva
dasilva at alum.mit.edu
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