[theil_2.md] Update np.random → Generator API

[Chihiro2000GitHub]

Summary

This PR migrates legacy NumPy random API usage in theil_2.md as part of QuantEcon/meta#299.

The seeded np.random.seed(...) / np.random.randn(...) pattern in the cell that plots standard against robust consumption paths is replaced with an explicit seeded generator rng = np.random.default_rng(0).

Related PRs and issues

I checked for open PRs and issues related to this lecture. No open PR modifies theil_2.md. Issue #990 lists theil_2.md among the lectures with dangling citation keys, but the fix there is to quant-econ.bib rather than to this file, and this PR does not attempt to address it.

Details

• np.random.seed(0) → rng = np.random.default_rng(0), and np.random.randn(T_sim - 1) → rng.standard_normal(T_sim - 1).
• The existing seed (0) is kept, and rng is local to the cell that uses it, so no hidden global random state remains.
• Both panels of the figure continue to share the same shock_path, so the comparison between the standard and robust policies is unaffected.
• No prose changes were needed: the text does not refer to np.random, and it describes the paths qualitatively rather than by their realized values.
• The lecture contains no Numba (@jit, @njit, @jitclass, parallel=True, prange) code.
• A full local build completed successfully and theil_2.md executed without errors.

Note for reviewers

The figure changes: default_rng draws from a different stream than the legacy API, so the same seed gives different draws. The rebuilt figure shows the same pattern as the current one.

Hi @mmcky and @HumphreyYang, I'd be grateful if you could take a look when you have time.

[github-actions]

📖 Netlify Preview Ready!

Preview URL: https://pr-1005--sunny-cactus-210e3e.netlify.app

Commit: e2dee3d

📚 Changed Lectures

• theil_2

---

Build Info

• Workflow: Build Project [using jupyter-book]