Improve interpolation performance

[rettigl]

replace scipy.interpolate.RegularGridInterpolator by scipy.ndimage.map_coordinates for a substantial improvement

of binning performance with momentum correction

Closes #357

[coveralls]

Pull Request Test Coverage Report for Build 8286464547

Details

• 23 of 31 (74.19%) changed or added relevant lines in 1 file are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 91.369%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sed/calibrator/momentum.py	23	31	74.19%

Files with Coverage Reduction	New Missed Lines	%
sed/calibrator/momentum.py	5	86.08%

Totals
Change from base Build 8230697770:	-0.1%
Covered Lines:	5992
Relevant Lines:	6558

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💛 - Coveralls

[rettigl]

I tested this again on the maxwell jhub, and there the speedup is really tremendous. Old version is ~70-80 s per iteration, new is 10:

And indeed, both produce identical results.

[zain-sohail]

It isn't quite clear to me why the map_coordinates is faster than scipy's interpolate method. But of course, those are seperate modules and seem to have very different implementations.

The parallelization is a nice addition. Everything seems good

[rettigl]

It isn't quite clear to me why the map_coordinates is faster than scipy's interpolate method. But of course, those are seperate modules and seem to have very different implementations.

The parallelization is a nice addition. Everything seems good

For comparison of different methods see e. g. here: https://stackoverflow.com/questions/53857403/scipy-interpolation-speed-is-there-anything-faster-than-rectbivariatespline