r/generate_ndset: Add inverted-simplex and concave-simplex shapes, fix convex-simplex

[Copilot]

Mirrors Python commit 0ddc3ba — adds two new generate_ndset() shapes to the R package and corrects the convex-simplex computation.

Changes

r/R/generate.R

• convex-simplex: Fixed implementation from sample_sphere()^4 → sample_simplex()^2 (more uniform)
• New methods: "inverted-simplex" / "inverted-linear" (1 - simplex) and "concave-simplex" (1 - convex-simplex)
• Updated all docs/descriptions to match Python, including new IshHeSha2019regular citations for inverted convex / inverted concave terminology

r/vignettes/articles/generate.Rmd

• Added new methods to 2D scatter plot
• Updated convex-simplex description (squares simplex points, not sphere transform)
• New Inverted shapes section with three side-by-side 3D plots comparing regular vs. inverted variants

r/NEWS.md

• Added changelog entry for new shapes and convex-simplex behaviour change

Usage

generate_ndset(100, 3, "inverted-simplex", seed = 42)
generate_ndset(100, 3, "concave-simplex",  seed = 42)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.32%. Comparing base (0ddc3ba) to head (06c7605).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #60      +/-   ##
==========================================
+ Coverage   76.31%   76.32%   +0.01%     
==========================================
  Files          66       66              
  Lines        6599     6603       +4     
  Branches     1127     1127              
==========================================
+ Hits         5036     5040       +4     
  Misses       1255     1255              
  Partials      308      308              

Flag	Coverage Δ
R	65.42% <100.00%> (+0.02%)	⬆️

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Components	Coverage Δ
tests	100.00% <ø> (ø)
src	86.88% <ø> (ø)

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