Re: Ruby + NCL

On Tue, 27 May 2008, Saji N. Hameed wrote:

> Dear NCL Developers and all,
>
> We are developing a Ruby Rails + NCL based web application to
> serve our climate forecast products. So far so good... we
> use the "system" and similar functions in ruby to run NCL as a child
> process.
>
> Having heard about PyNCL I was wondering if a similar interface
> to NCAR graphics could be made using Ruby. As a first step,
> we have succeeded in using NArray and friends in ruby to
> facilitate I/O and basic array operations.

Hi Saji and others,

Just to make sure things are clear here: PyNCL is something that Jeff
Whitaker of NOAA created which allows you to create NCL plots of CDMS
variables:

   http://www.cdc.noaa.gov/people/jeffrey.s.whitaker/python/pyncl.html

Jeff has created several really useful Python modules, including an
interface to Spherepack, a GRIB2 reader, and a nice mapping
interface that ties into matplotlib:

   http://www.cdc.noaa.gov/people/jeffrey.s.whitaker/

PyNGL (developed by Fred Clare and myself) is a set of Python bindings
that mimic some of the generic gsn_xxxx plotting functions. These
functions were written in C, and swig was used to wrap some of the
underlying low-level codes (the routines in the HLU API library, to
name a few).

    http://www.pyngl.ucar.edu/

PyNIO (developed by Dave Brown) gives you a similar file I/O handling
interface that NCL has, allowing you to open NetCDF, HDF4, GRIB1/GRIB2
files with a single "Nio.open_file" call (similar to NCL's
"addfile").

    http://www.pyngl.ucar.edu/Nio.shtml

In the next release of PyNIO, we'll have some extensive coordinate
subscripting capability.

> We are aware that SWIG (http://www.swig.org/) can be used to
> connect C programs with higher-level languages including
> Ruby and Python. Could somebody provide advice and if possible
> some help to develop a ruby binding for NCAR graphics?

Unfortunately, developing Ruby interfaces is not something that we
have time to add to our list right now. Developing NCL and the Python
bindings have kept us pretty busy so far!

When we go fully open source with PyNGL and PyNIO, you will be able to
download the C programs we used for creating the plotting routines,
and perhaps you can wrap these for Ruby.

By the way, we are very interested in hearing people's ideas on these
various scripting languages, especially as they are used in the
scientific genre. If you don't want to post back to ncl-talk, feel free
to email your comments to me, and I'll share them with the other
NCL developers.

--Mary

> cheers,
> saji
>
> --
> Saji N. Hameed
>
> APEC Climate Center +82 51 668 7470
> National Pension Corporation Busan Building 12F
> Yeonsan 2-dong, Yeonje-gu, BUSAN 611705 saji_at_apcc21.net
> KOREA
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> ncl-talk_at_ucar.edu
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>
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Received on Tue May 27 2008 - 10:08:52 MDT