[gradsusr] issue in exporting and expression, change it in Python and import back

[Helio Camargo]

Dear gradsusr,

Just before mentioning the error, I like to emphasize that the environment
variables GAUDXT and LD_LIBRARY_ PATH are (apparently) properly set in my
.bashrc.

I've been struggling a bit just to follow a pygrads example available in
http://opengrads.org/wiki/index.php?title=PyGrADS_Interactive_Shell .
Everytime I want to export and expression, change it in Python and import
back I get the following message:


***********
iuser at iuser-Dell-System-Vostro-3450:~$ pygrads

  Welcome to PyGrADS, a GrADS-based iPython environment.

Grid Analysis and Display System (GrADS) Version 2.0.a9.oga.1
Copyright (c) 1988-2010 by Brian Doty and the
Institute for Global Environment and Society (IGES)
GrADS comes with ABSOLUTELY NO WARRANTY
See file COPYRIGHT for more information

Config: v2.0.a9.oga.1 little-endian readline printim grib2 netcdf hdf4-sds
hdf5 opendap-grids,stn athena geotiff shapefile
Issue 'q config' command for more detailed configuration information
Loading User Defined Extensions table
</opt/opengrads/Linux/Versions/2.0.a9.oga.1/i686/gex/udxt> ... ok.
GX Package Initialization: Size = 11 8.5


   Welcome to PyGrADS, a GrADS-based iPython environment.
   For more information, type 'help(ipygrads)'

?         -> Introduction and overview of IPython's features.
help      -> Python's own help system.
qref      -> PyGrADS quick reference
examples  -> Some PyGrADS examples
object?   -> Details about 'object'. ?object also works, ?? prints more.



 [2] ga-> o model
Scanning description file:  model
Data file model.grb is open as file 1
LON set to 0 360
LAT set to -90 90
LEV set to 1000 1000
Time values set: 1987:1:1:0 1987:1:1:0
E set to 1 1


 [3] ga-> . q dims
Default file number is: 1
X is varying   Lon = 0 to 360   X = 1 to 73
Y is varying   Lat = -90 to 90   Y = 1 to 46
Z is fixed     Lev = 1000  Z = 1
T is fixed     Time = 00Z01JAN1987  T = 1
E is fixed     Ens = 1  E = 1


 [4] ga-> . set lev 300
LEV set to 300 300


 [5] ga-> uv = ga.exp('ua*ua+va*va')

 [6] ga-> speed = sqrt(uv)

 [7] ga-> ga.imp('speed', speed)

------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/grads/ganum.py", line 336, in
imp
    t1_, z1_ = (grid.denv.t[0], grid.denv.z[0])
AttributeError: 'NoneType' object has no attribute 't'


 [8] ga-> ga.imp('speed', speed)
^[[A
^C------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/grads/ganum.py", line 298, in
imp
    dh = self.query("dims", Quiet=True)
  File "/usr/local/lib/python2.7/dist-packages/grads/gacore.py", line 494,
in query
    self.cmd('query '+what,Quiet)
  File "/usr/local/lib/python2.7/dist-packages/grads/gacore.py", line 241,
in cmd
    rc = self._parseReader(Quiet)
  File "/usr/local/lib/python2.7/dist-packages/grads/gacore.py", line 1051,
in _parseReader
    got = self.Reader.readline()
KeyboardInterrupt


 [9] ga->
^C
************

The funny thing is that after I try it once, the second try gets stuck and
only CTRL+C returns the prompt back...

Any hint on what can be going on will be very welcome.

Thx in advance,

--
Helio
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