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manoharan-lab / holopy

Hologram processing and light scattering in python
GNU General Public License v3.0
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Composescatteringtheory v2 #378

Closed briandleahy closed 3 years ago

briandleahy commented 3 years ago

The same as #377, but modified to keep the git blame for each line of code despite the split of scatteringtheory into two files. I've kept the commit hashes exactly the same.

Since this PR should be the one that gets merged in, I've copied the notes from #377 below.

This PR composes out a lot of the work of the old ScatteringTheory class into two new classes, a (much lighter) ScatteringTheory and a new ImageFormation class.

Rationale Most of the old ScatteringTheory code was actually for calculating images and not for scattering calculations per se. This made creating and modifying new scattering theories unwieldy. In particular, it was difficult to know which methods needed to be implemented to create a new scattering theory. This is now fixed. Moreover, while most of the time in a hologram calculation (say) was spent in the old ScatteringTheory class, that time is mostly in dealing with xarrays and not in doing scattering calculations per se. Now that these two responsibilities are separated, performance optimizations will be easier to implement.

Code Changes The code that was previously in holopy.scattering.theory.scatteringtheory is now split between holopy.scattering.theory.scatteringtheory and holopy.scattering.imageformation. In addition, there were some minor changes to the individual scattering theories, particularly the Lens theory, to work with the new changes. (The Lens theory relied on methods which were moved to the ImageFormation class; now it only relies on ScatteringTheory methods.)

API Changes All of these changes are internal and not visible to outside users.

briandleahy commented 3 years ago

Arg, this preserves the blame for imageformation.py but not scatteringtheory.py Not sure what to do here...

barkls commented 3 years ago

Here's a series of blog posts about how to do this. It looks from the first one like you might be able to rename both files before merging, and then rename one back afterwards, although he doesn't explicitly say that. The second and third methods are a bit more convoluted but he specifically shows they do work. Sorry if I misled you!

https://devblogs.microsoft.com/oldnewthing/20190916-00/?p=102892 https://devblogs.microsoft.com/oldnewthing/20190917-00/?p=102894 https://devblogs.microsoft.com/oldnewthing/20190918-00/?p=102901

briandleahy commented 3 years ago

Superseded by #379