Multidimensional SAX (and fixes to HOT-SAX)

[ameya98]

Implements extensions to multi-dimensional SAX via SAX-ZSCORE and SAX-REPEAT from Robust learning from demonstrations using multidimensional SAX, as well as a new method SAX-ENERGY (that performs SAX along the data-dimensions). Fixes off-by-one errors in HOT-SAX, sax_by_window and the brute force method for discords. Further, reimplements VisitRegistry as a set.

[codecov]

Codecov Report

Merging #8 into master will decrease coverage by 11.44%.
The diff coverage is 65.86%.

@@             Coverage Diff             @@
##           master       #8       +/-   ##
===========================================
- Coverage   86.68%   75.24%   -11.45%     
===========================================
  Files          12       12               
  Lines         338      412       +74     
===========================================
+ Hits          293      310       +17     
- Misses         45      102       +57

Impacted Files	Coverage Δ
saxpy/discord.py	100% <100%> (ø)	⬆️
saxpy/hotsax.py	100% <100%> (ø)	⬆️
saxpy/visit_registry.py	100% <100%> (ø)	⬆️
saxpy/distance.py	100% <100%> (ø)	⬆️
saxpy/sax.py	53.7% <36.7%> (-46.3%)	⬇️
saxpy/znorm.py	77.27% <75%> (-22.73%)	⬇️
saxpy/paa.py	92.59% <91.3%> (-7.41%)	⬇️

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[codecov]

Codecov Report

Merging #8 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #8   +/-   ##
=======================================
  Coverage   87.94%   87.94%           
=======================================
  Files          12       12           
  Lines         423      423           
=======================================
  Hits          372      372           
  Misses         51       51

---

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Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[ameya98]

Added doctests for coverage - should be okay now.

[ameya98]

I also added SAX-INDEPENDENT to sax_via_window(). This applies SAX independently to each dimension and concatenates the SAX words. Doctests have been written too, in sax_via_window().

[ameya98]

The current HOT-SAX implementation is quite inefficient - both the SAX words and the znormalized subsequences only need to be computed once. I've improved HOT-SAX by making these changes. Runtime performance is now better by 10x-20x.