[MRG] replace chernoff bounds with exact probabilities

[dkoslicki]

Please replace this text with:

• See issue ANI/AAI estimates being zero'd out too aggressively #2267. in brief: Much better to use the exact probabilities, so we don't zero out ANI/AAI estimates when dealing with shorter sequences
• Fixes ANI/AAI estimates being zero'd out too aggressively #2267 2267

No file format, CLI, or API changes (save for a very small function)

[codecov]

Codecov Report

Merging #2268 (b876e22) into latest (569d212) will increase coverage by 7.29%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           latest    #2268      +/-   ##
==========================================
+ Coverage   84.85%   92.14%   +7.29%     
==========================================
  Files         131      100      -31     
  Lines       15669    11400    -4269     
  Branches     2250     2251       +1     
==========================================
- Hits        13296    10505    -2791     
+ Misses       2082      601    -1481     
- Partials      291      294       +3     

Flag	Coverage Δ
python	92.14% <100.00%> (-0.05%)	⬇️
rust	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/sourmash/distance_utils.py	99.39% <100.00%> (+0.02%)	⬆️
src/sourmash/minhash.py	94.05% <100.00%> (ø)
src/sourmash/commands.py	90.12% <0.00%> (-0.67%)	⬇️
src/core/src/ffi/signature.rs
src/core/src/index/linear.rs
src/core/src/errors.rs
src/core/src/ffi/hyperloglog.rs
src/core/src/ffi/index/revindex.rs
src/core/src/index/mod.rs
src/core/src/lib.rs
... and 24 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[dkoslicki]

Apparently there were tests I wasn't aware of. Will try to get to them soon (looks to be an easy, if not tedious, fix)

[ctb]

most of the errors seem to be "hey, you're setting ANI now and you weren't before!" so that's good ;). And a few where the value change. But if those are the only tests that break (i.e. expected ones from changing some analytical results) then you're in good shape.

There's one test, test_containment_ani_ci_tiny_testdata in test_minhash.py, that looks like it might be trickier, but that's it.

[dkoslicki]

Ok, I think it's ready for a review @ctb! Apparently I can't tag @sourmash-bio/devs

[ctb]

Apparently I can't tag sourmash-bio/devs

you should be able to now! and you have the ability to set up PRs directly in this repo too (or at least an invitation to those powers on the repo). but no need to do so for this PR.