[Opengrads-users] Working through OpenGrADS Examples

[brown w. <gr...@ya...>]

I am working through the OpenGrADS examples and have come across one that doesn't work:


[3] ga-> uv = ga.exp('ua*ua+va*va')
/usr/lib/python2.6/site-packages/pygrads-1.1.8-py2.6.egg/grads/numtypes.py:131: DeprecationWarning: object.__init__() takes no parameters
  ma.MaskedArray.__init__(self,data, **kwargs)

 [4] ga-> speed = sqrt(uv)

 [5] ga-> dd speed

Traceback (most recent call last):
  File "<ipython-input-5-ecf94a228a9d>", line 1, in <module>
    get_ipython().magic(u'dd speed')
  File "/usr/lib/python2.6/site-packages/IPython/core/interactiveshell.py", line 2172, in magic
    return self.run_line_magic(magic_name, magic_arg_s)
  File "/usr/lib/python2.6/site-packages/IPython/core/interactiveshell.py", line 2093, in run_line_magic
    result = fn(*args,**kwargs)
  File "/usr/lib/python2.6/site-packages/pygrads-1.1.8-py2.6.egg/ipygrads.py", line 411, in gad
    ip_Exec(self,"ga.imp('<display>',%s)"%(arg))
  File "/usr/lib/python2.6/site-packages/pygrads-1.1.8-py2.6.egg/ipygrads.py", line 152, in ip_Exec
    ip.ex(cmd)
  File "/usr/lib/python2.6/site-packages/IPython/core/interactiveshell.py", line 2446, in ex
    exec cmd in self.user_global_ns, self.user_ns
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.6/site-packages/pygrads-1.1.8-py2.6.egg/grads/ganum.py", line 336, in imp
    t1_, z1_ = (grid.denv.t[0], grid.denv.z[0])
AttributeError: 'NoneType' object has no attribute 't'


 [6] ga-> 


Any ideas as to what might be wrong? Thanks.