[ENH] PC algorithm with updated example using dowhy.gcm for the SCM module

[adam2392]

Fixes #18
Closes: #10

Changes proposed in this pull request:

• This supersedes [ENH] Add PC algorithm #18
• This is a "big PR", but the example goes hand-in-hand w/ the algorithm implementation. In general, I think any PR with "algorithms" should require at least a corresponding example, if not corresponding example + in-depth tutorial

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[robertness]

I'm okay with this so long as my requests are addressed.

Also, can you double check that you have tests in place that will protect this code against pending refactors to the context object?

[codecov-commenter]

Codecov Report

Merging #30 (a8fba22) into main (5b7465b) will increase coverage by 10.71%.
The diff coverage is 81.11%.

@@             Coverage Diff             @@
##             main      #30       +/-   ##
===========================================
+ Coverage   68.04%   78.75%   +10.71%     
===========================================
  Files          13       14        +1     
  Lines         679      805      +126     
  Branches      126      157       +31     
===========================================
+ Hits          462      634      +172     
+ Misses        175      118       -57     
- Partials       42       53       +11     

Impacted Files	Coverage Δ
dodiscover/ci/oracle.py	86.95% <ø> (ø)
dodiscover/_protocol.py	60.52% <64.28%> (-1.02%)	⬇️
dodiscover/constraint/pcalg.py	79.61% <79.61%> (ø)
dodiscover/context.py	82.14% <90.90%> (+14.75%)	⬆️
dodiscover/constraint/_classes.py	81.42% <100.00%> (+81.42%)	⬆️
dodiscover/constraint/skeleton.py	75.64% <100.00%> (+5.12%)	⬆️
dodiscover/constraint/utils.py	61.53% <100.00%> (+15.38%)	⬆️
dodiscover/typing.py	100.00% <100.00%> (ø)
... and 2 more

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

[adam2392]

Also, can you double check that you have tests in place that will protect this code against pending refactors to the context object?

The context object is only accessed through its class properties rn and then the instantiations are used in the unit tests. They are used in conjunction w/ the PC algo, so in principle changes to the context that break PC algo, will be detected by those tests.

I've addressed most of your comments, except #30 (comment). In addition, some misc. topics:

• The inclusion/exclusion of edges I think is a larger issue, which I've begun a thread in [ENH] Add required/excluded edge directions in the orientation phase of PC/FCI #46.
• Another lower-pri item is the refactoring of CI tests into functions [Refactor] Change all CI tests from classes into functions #45

[robertness]

I think we should get this merged if there are no further concerns

[robertness]

I agree that we can address include/exclude edge issues elsewhere.

[adam2392]

I agree that we can address include/exclude edge issues elsewhere.

Sorry can you re-approve? Fixing the merge conflicts inside changelog and conf.py and it disables your previous approval :(

[robertness]

Reapproving