Issue 175: Plot identity vs coverage scatter plot

[baileythegreen]

Plots an identity vs coverage scatter plot.
Closes #175. (Maybe.)

Documentation has not been added because the file it would go in is in #305, which has not yet been merged.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality not to work as expected)
• This change requires a documentation update
• This is a documentation update

(The relevant documentation update is dependent upon #305, though.)

Action Checklist

• Work on a single issue/concept (if there are multiple separate issues to address, please use a separate pull request for each)
• Fork the pyani repository under your own account (please allow write access for repository maintainers)
• Set up an appropriate development environment (please see CONTRIBUTING.md)
• Create a new branch with a short, descriptive name
• Work on this branch
  • style guidelines have been followed
  • new code is commented, especially in hard-to-understand areas
  • corresponding changes to documentation have been made
  • tests for the change have been added that demonstrate the fix or feature works
• Test locally with pytest -v non-passing code will not be merged
• Rebase against origin/master
• Check changes with flake8 and black before submission
• Commit branch
• Submit pull request, describing the content and intent of the pull request
• Request a code review
• Continue the discussion at Pull requests section in the pyani repository

[baileythegreen]

@widdowquinn Tests on this are now failing for a reason unrelated to the code. See Issue #330 for details.

[codecov]

Codecov Report

Merging #319 (30e5c5f) into master (9435a5e) will increase coverage by 0.27%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #319      +/-   ##
==========================================
+ Coverage   75.85%   76.12%   +0.27%     
==========================================
  Files          52       52              
  Lines        3342     3380      +38     
==========================================
+ Hits         2535     2573      +38     
  Misses        807      807              

[widdowquinn]

I don't think that label info will end up being incorporated here. Labels apply to single genomes, not pairwise comparisons. Could just delete this commented-out section for now. We can discuss ideas for colouring points on the plot elsewhere.

[widdowquinn]

Looks good, please merge. We should think of ways to indicate colour/regions on the plot that could be helpful to the user (e.g. "same species"/"same genus" etc.).