Raise error if pop passed to samples is not an integer

[hyanwong]

Description

This has bugged me for ages: you can do ts.samples(population="AFR") without raising an error, although the population param is required to be an integer (so that snippet will always return an empty array)

I thought using int was the simplest way to check, as it avoids isinstance(population, string) or equivalent, and will deal with arrays etc, but it does allow ts.samples(population="0"), which maybe we don't want?

PR Checklist:

• Tests that fully cover new/changed functionality.
• Documentation including tutorial content if appropriate.
• Changelogs, if there are API changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.76%. Comparing base (f1b139e) to head (15fd849).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3344   +/-   ##
=======================================
  Coverage   89.76%   89.76%           
=======================================
  Files          29       29           
  Lines       31289    31292    +3     
  Branches     5737     5738    +1     
=======================================
+ Hits        28086    28089    +3     
  Misses       1794     1794           
  Partials     1409     1409           

Flag	Coverage Δ
c-tests	86.77% <ø> (ø)
lwt-tests	80.38% <ø> (ø)
python-c-tests	87.12% <ø> (ø)
python-tests	98.85% <100.00%> (+<0.01%)	⬆️
python-tests-no-jit	33.51% <0.00%> (-0.02%)	⬇️
python-tests-numpy1	50.28% <100.00%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
python/tskit/trees.py	98.89% <100.00%> (+<0.01%)	⬆️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jeromekelleher]

This needs much more testing - just testing for one example when doing this type of type handling really isn't enough.

[hyanwong]

Changes made and squashed.

We still don't have a good newbie solution for "get all the samples in the population named 'AFR'" though. At the moment I guess we recommend making a map, but that's not very beginner friendly:

name_to_id = {pop.metadata["name"]: pop.id for pop in ts.populations()}
ts.samples(name_to_id["AFR"])

See #1697 where I suggest ts.samples(population={'name':'EUR'})

[hyanwong]

I'm waiting for this to merge so I can rebase #3345 . What's the etiquette here: if there is one approval, can the OP (me) click the merge button, or should I get someone else to do it? Do we require two approvals (I think not?)