"Invalid Input Data" From SciPy's Cublic Spline Interpolation Process; Bad Results From Interpolate.bisplrep?

I'm attempting to use scipy.interpolate.bisplrep and scipy.interpolate.bisplev to perform a 2D regression on the differences between two datasets, based on a small set of known dif

Solution 1:

From my past experience with this problem, features[0] and features[1] must be sorted in ascending order for bisplev to work.