extracting from pyGrADs

Arlindo da Silva dasilva at ALUM.MIT.EDU
Tue May 13 14:25:51 EDT 2008

On Tue, May 13, 2008 at 12:59 PM, Shun Jie Liu <shun.jie.liu at invenia.ca>

>  Hi GrADs users,
> I am using pyGrADs and went through the examples adn tutorial and
> everything seems ok.

What is your platform? Please send output of

uname -a
python --version
ga('q config')
ga('q udct')

> I can display variable T2 using my own data file on iPython using
> d T2

This is good.

> However, when I try to extract from the data file using
> xx T2
> I got an error,
> <class 'grads.gacore.GrADSError'>: 'invalid exchange metadata
> (idim,jdim)=(0,-2147483648) - make sure <T2> is valid and that lon/lat is
> varying
> From the error, it looks like there is a buffer overflow on jdim...but how
> is this possible ?

The first part of the code reads a header from the pipe to determine the
dimension environment of the chunk of data to be read. In this case, jdim
should be 1 which says that this is a lat-lon 2D field. I am not sure what
is going on.

> Since I can show T2 graphically, I assume T2 is valid. So I tried 'q dims'
> to check I get.
> X is varying Lon = -100.923 to -95.6679 X = 0.999873 to 351
> Y is varying Lat = 48.0392 to 50.9668 Y = 1.00022 to 196
> Z is fixed
> T is fixed

To be sure we are not running into float point accuracy issues, could you
please set you dimension environment in index space. Try this:

ga('set x 1 351')
ga('set y 1 196')
t2 = ga.exp('t2')

If the problem persists it would be better if you can make your file
available to me.


Arlindo da Silva
dasilva at alum.mit.edu
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