finalise kernel constructors in graph

[martinfleis]

• taper is back and working properly.
• kernel constructors are tested
• fixed issues with conincident points
• exposes sklearn metrics outside knn

One question:

What shall be the behaviour of kernel when k is set but the bandwidth s too small so weight is zero, eliminating the link with taper? now the affected focal has less neighbors than K without a warning. I'd say we may warn but that is about it. You can retrieve the rest using taper=False.

edited

[codecov]

Codecov Report

Merging #571 (4a149c1) into main (c8456c8) will increase coverage by 0.4%.
The diff coverage is 99.2%.

@@           Coverage Diff           @@
##            main    #571     +/-   ##
=======================================
+ Coverage   81.6%   82.0%   +0.4%     
=======================================
  Files        128     128             
  Lines      14937   15156    +219     
=======================================
+ Hits       12186   12430    +244     
+ Misses      2751    2726     -25     

Files Changed	Coverage Δ
libpysal/graph/_triangulation.py	98.0% <ø> (ø)
libpysal/graph/_kernel.py	88.5% <95.2%> (+17.3%)	⬆️
libpysal/graph/_contiguity.py	98.9% <100.0%> (-0.1%)	⬇️
libpysal/graph/_utils.py	93.1% <100.0%> (+0.7%)	⬆️
libpysal/graph/base.py	95.6% <100.0%> (ø)
libpysal/graph/tests/test_kernel.py	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes

[jGaboardi]

Any idea what's going on with the failures?

[martinfleis]

Yes, will fix

[jGaboardi]

Whoops, approved too soon.

[martinfleis]

@jGaboardi should be fixed now. I was too lazy to create an env without sklearn and it shows...

[martinfleis]

Gonna merge and continue with triangulation. Feel free to still review this, we can fix stuff in follow-ups.