Fix latex rendering of variables with underscore in name

[Dekermanjian]

Description

I added a simple fix to LaTeX Repr that escapes variables that have underscores in them and I created a unit test to test the fix.

Related Issue

• Closes BUG: KaTeX parse error on Jupyter Notebook when using underscore, etc. #6508
• Related to Latex_ in variable names is not properly escaped #7495 and Refactor pretty-printing and fix latex underscores #6533

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks)
• If you are a pro: each commit corresponds to a [relevant logical change]

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):

---

📚 Documentation preview 📚: https://pymc--7501.org.readthedocs.build/en/7501/

[Dekermanjian]

Hey @ricardoV94, I added a simplistic fix to address the underscores breaking the KaTeX output in VSCode and Jupyter. I tested in VSCode and Jupyter Lab. Are there any other environments I should test it out in?

Hmm actually, it is not working now in Jupyter for me. Let me figure out what happened.

Oh never mind, I was just not selecting the proper environment. It does work in Jupyter Lab.

[Dekermanjian]

Hey @twiecki, I think some of the tests failed because they expect the LaTeX representation of underscores to be unescaped. Would it be okay, to modify those tests so that they expect underscores for LaTeX to be escaped?

[twiecki]

Hey @twiecki, I think some of the tests failed because they expect the LaTeX representation of underscores to be unescaped. Would it be okay, to modify those tests so that they expect underscores for LaTeX to be escaped?

Yes.

[Dekermanjian]

Hey @twiecki, I applied the underscore escaping function to also work at the distribution level within a model. So both calling objects holding distributions or calling the entire model will escape underscore variables for LaTeX representation. I also changed the expected string objects in the testing script to expect that underscores in LaTeX be escaped.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.43%. Comparing base (d596afb) to head (4156804).
Report is 14 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7501      +/-   ##
==========================================
+ Coverage   92.16%   92.43%   +0.26%     
==========================================
  Files         103      103              
  Lines       17200    17109      -91     
==========================================
- Hits        15853    15814      -39     
+ Misses       1347     1295      -52     

Files with missing lines	Coverage Δ
pymc/printing.py	87.41% <100.00%> (+0.43%)	⬆️

... and 19 files with indirect coverage changes

[welcome]

]
Congrats on merging your first pull request! 🎉 We here at PyMC are proud of you! 💖 Thank you so much for your contribution 🎁