Hi Sam,
Unfortunately there is currently no way to create an NioVariable in memory. I can certainly see the need for it in the use case you have presented. A workaround might be to create an actual temporary NetCDF file with the derived SPEED variable added. I think the latest versions of NetCDF have the capability to create NetCDF "files" in memory. If we can add support for this feature that could make such a workaround be efficient as well. But adding support for a stand-alone NioVariable would be a good idea as well. Sorry there is not a better answer at the moment.
-dave
On Sep 26, 2012, at 8:11 AM, pyngl-talk-bounces@ucar.edu wrote:
>
> From: <sam.hawkins@vattenfall.com>
> Date: September 26, 2012 8:10:55 AM MDT
> To: <pyngl-talk@ucar.edu>
> Subject: Derived variables from grib file
>
>
> Dear PyNGL users,
>
> I'm working with GRIB files, and want to create the derived variable SPEED (in memory) from U and V wind components. I want this to be an NioVariable object with the same named dimensions as the components, so that I can use the extended selection syntax to interpolate. However, I can't use the create_variable method, since grib files are not writeable using Nio. Is it possible to create an NioVariable in memory only? I'm sure I've done this in NCL before.
>
> Sam.
>
>
> Sam Hawkins
> R&D Engineer
>
> Vattenfall Research & Development
> Business Division Asset Development
> New Renewables
>
> sam.hawkins@vattenfall.com
>
>
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Received on Thu Sep 27 22:32:06 2012
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