[SciPy-User] NetcdfIntepolatingFunction

[Johannes Korn]

Hi,

I´d like to use "NetcdfIntepolatingFunction" to obtain values from an 
ECMWF-Reanalysis file interpolated in time and space.

I tried:

In [88]: 
a=Scientific.Functions.Interpolation.NetCDFInterpolatingFunction('output2.nc',['longitude','latitude','time'],'u10',default=-99.)

In [90]: a(0,0,899940)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)

/home/users/rein_be/cloudprops/compare_albedos/tmp/<ipython console> in 
<module>()

/usr/local/lib/python2.6/site-packages/Scientific/Functions/Interpolation.pyc 
in __call__(self, *points)
      90                 pass
      91         try:
---> 92             neighbours = map(_lookup, points, self.axes, 
self.period)
      93         except ValueError, text:
      94             if self.default is not None:

/usr/local/lib/python2.6/site-packages/Scientific/Functions/Interpolation.pyc 
in _lookup(point, axis, period)
     436             raise ValueError('Point outside grid of values')
     437         i = j-1
--> 438         weight = (point-axis[i])/(axis[j]-axis[i])
     439         return index_expression[i:j+1:1], weight
     440     else:

TypeError: illegal subscript type





Interestingly if I swap the axes ('time' now on 1st position) I´m able 
to call 'a':

In [91]: 
a=Scientific.Functions.Interpolation.NetCDFInterpolatingFunction('output2.nc',['time','longitude','latitude'],'u10',default=-99.)

In [92]: a(0,0,899940)
Out[92]: -99.0




However, if I also swap axes in the calling command:


In [93]: a(899940,0,0)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)

/home/users/rein_be/cloudprops/compare_albedos/tmp/<ipython console> in 
<module>()

/usr/local/lib/python2.6/site-packages/Scientific/Functions/Interpolation.pyc 
in __call__(self, *points)
      90                 pass
      91         try:
---> 92             neighbours = map(_lookup, points, self.axes, 
self.period)
      93         except ValueError, text:
      94             if self.default is not None:

/usr/local/lib/python2.6/site-packages/Scientific/FunctionsIn [93]: 
a(899940,0,0)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)

/home/users/rein_be/cloudprops/compare_albedos/tmp/<ipython console> in 
<module>()

/usr/local/lib/python2.6/site-packages/Scientific/Functions/Interpolation.pyc 
in __call__(self, *points)
      90                 pass
      91         try:
---> 92             neighbours = map(_lookup, points, self.axes, 
self.period)
      93         except ValueError, text:
      94             if self.default is not None:

/usr/local/lib/python2.6/site-packages/Scientific/Functions/Interpolation.pyc 
in _lookup(point, axis, period)
     436             raise ValueError('Point outside grid of values')
     437         i = j-1
--> 438         weight = (point-axis[i])/(axis[j]-axis[i])
     439         return index_expression[i:j+1:1], weight
     440     else:

TypeError: illegal subscript type
/Interpolation.pyc in _lookup(point, axis, period)
     436             raise ValueError('Point outside grid of values')
     437         i = j-1
--> 438         weight = (point-axis[i])/(axis[j]-axis[i])
     439         return index_expression[i:j+1:1], weight
     440     else:

TypeError: illegal subscript type


Am I doing things wrong or is this a bug?

Kind regards!

Johannes