interpolation with python numpy
See the interpolation method in the numpy documentation that has examples:
http://docs.scipy.org/doc/numpy/reference/generated/numpy.interp.html
There are also a more extensive set of methods available through scipy:
I couldn't find anything similar to Matlab's fast interpn function, so I coded one myself:
https://github.com/fejikso/interpolator
It requires the data to be in a grid, but the coordinates don't need to be equally spaced.