Extrapolate with LinearNDInterpolator

Question

I\'ve got a 3D dataset that I want to interpolate AND extrapolate linearly. The interpolation can be done easily with scipy.interpolate.LinearNDInterpolator. The module can

Answer 1

use combination of nearest and linear interpolation. LinearNDInterpolator returns np.nan if it fails to interpolate otherwise it returns an array size(1) NearestNDInterpolator returns a float

import scipy.interpolate
import numpy
class LinearNDInterpolatorExt(object):
  def __init__(self, points,values):
    self.funcinterp=scipy.interpolate.LinearNDInterpolator(points,values)
    self.funcnearest=scipy.interpolate.NearestNDInterpolator(points,values)
  def __call__(self,*args):
    t=self.funcinterp(*args)
    if not numpy.isnan(t):
      return t.item(0)
    else:
      return self.funcnearest(*args)