[SciPy-Dev] Bivariate interpolation and NaN

Gael Varoquaux gael.varoquaux@normalesup....
Fri Jun 10 02:13:35 CDT 2011


On Fri, Jun 10, 2011 at 01:01:24AM -0600, Charles R Harris wrote:
>    I think both are expected. Splines are a global fit and nans will cause
>    global trouble. Likewise, splines can exhibit ringing. You can use a
>    smoothing spline to get around that, but it won't interpolate the data
>    points exactly. It sounds to me like you want something local, for
>    instance bi-cubic interpolation or bilinear (the algorithm name). There
>    are some tools for this sort of thing in scipy.ndimage, and tools like
>    gdal or imagemagick might also do what you want depending on the specifics
>    of the problem.

WENO interpolation (weighted essentially non-oscillatory):
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.148.8505&rep=rep1&type=pdf

http://www.scholarpedia.org/article/WENO_methods

Adrian Townsend presented such interpolation scheme at scipy a couple of
years ago: 
http://www.archive.org/details/scipy09_day1_14-Adrian_Townsend
He slides might actually be amongst the most readable material around:
http://conference.scipy.org/static/wiki/townsend_weno.pdf
anhd he has Python code:
http://memmett.github.com/PyWENO/

Gael


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