[Scipy-tickets] [SciPy] #1412: Bug in griddata (Code does not return)

SciPy Trac scipy-tickets@scipy....
Mon Mar 21 07:06:55 CDT 2011

#1412: Bug in griddata (Code does not return)
 Reporter:  schicketanz        |       Owner:  somebody
     Type:  defect             |      Status:  new     
 Priority:  high               |   Milestone:          
Component:  scipy.interpolate  |     Version:  0.9.0   
 Keywords:  griddata           |  
 I have found a bug in griddata. The code does not return in my example. It
 is difficult to reduce the data, because then the code  suddenly works. I
 have no idea what to do to locate the problem further.

 Here is the example code:

 import numpy as np
 from scipy.interpolate import griddata

 #coord is a circle with an regular grid
 coord = np.load('coord.data.npy')
 A = np.zeros(coord.shape[0])
 coordi = np.array([[ 0.02803372, -0.03142812]]) #This should return nan

 #This does not work (Code does not return)
 print griddata(coord, A, coordi)

 #The triangulation works
 from scipy.interpolate import LinearNDInterpolator
 ip = LinearNDInterpolator(coord, A, fill_value=np.nan)
 print 'triangulation works'

 #This works!
 #The point is outside the convex hull. The data near this point is defined
 by index
 index = (coord[:,0]>0.02) & (coord[:,0]<0.035) & (coord[:,1]>-0.04)
 print griddata(coord[index,:], A[index], coordi)

 #If the data is shifted or scaled the example works

Ticket URL: <http://projects.scipy.org/scipy/ticket/1412>
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