[SciPy-User] 1-d Interpolation of unevenly spaced data

[Dybbroe Adam]

Thanks.
Ok, I have stored my data in an npz-file (attached).
You should be able to run the following code (with the npz file in the 
same directory from where you run):

     import numpy as np
     outfile = './ipol_test_arrays.npz'

     from scipy.interpolate import splrep, splev

     # Load data and try do the spline interpolation:
     npzfile = np.load(outfile)
     wvl = npzfile['wvl']
     resp = npzfile['resp']
     xspl = np.linspace(wvl[0], wvl[-1], 300)

     tck = splrep(wvl, resp)
     resp_ipol = splev(xspl, tck)


Here is what I get:

In [1]: run scipy_ipol_test_ext.py
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)

/local_disk/laptop/NowcastingSaf/radiationStuff/test/scipy_ipol_test_ext.py 
in <module>()
      14     xspl = np.linspace(wvl[0], wvl[-1], 300)
      15
---> 16     tck = splrep(wvl, resp)
      17     resp_ipol = splev(xspl, tck)
      18

/home/a000680/usr/lib64/python2.5/site-packages/scipy/interpolate/fitpack.pyc 
in splrep(x, y, w, xb, xe, k, task, s, t, full_output, per, quiet)
     416         else:
     417             try:
--> 418                 raise _iermess[ier][1],_iermess[ier][0]
     419             except KeyError:
     420                 raise _iermess['unknown'][1],_iermess['unknown'][0]

ValueError:     Error on input data
WARNING: Failure executing file: <scipy_ipol_test_ext.py>


:-(

-Adam



On 2011-02-01 15:12, Christian K. wrote:
> Am 01.02.11 14:40, schrieb Dybbroe Adam:
>    
>> # Mask out part of the response curve:
>> maskidx = np.logical_and(np.greater_equal(w_ch, start),
>> np.less_equal(w_ch, end))
>> wvl = np.repeat(w_ch, maskidx)
>> resp = np.repeat(resp_ch, maskidx)
>>      
> I do not unterstand what those lines are for. As long as the
> interpolation range is within the data range everything is ok.
>
> Thus it is really suffienct to do
>
> tck = splrep(yourdata_x, yourdata_y)
> resp_ipol = splev(linspace(yourdata_x[0],yourdata_x[-1],200), tck)
>
> Maybe you could post a running script including your data.
>
> Regards, Christian
>
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>
>    

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