MAINT: bayes_opt.util.acq_max Lacking Some Forward Compatibility with Scipy L-BFGS-B Minimizer

[ngupta20]

Description

Scipy made a change starting in version 1.7.2 that ensures the attribute .fun of an OptimizeResult object returned by _minimize_lbfgsb is scalarized (from a low/zero-dimensional np.ndarray to a float). The pertinent change in scipy.optimize._differentiable_functions can be viewed here.

Reproduction

I happened upon the effects of the new scipy version when running a standard register-suggest on an updated environment.
This notebook contains the error reproduction and a view of the stack trace.

Suggested Change

I posted a low-impact, version-gnostic, and backwards compatible PR (#319). Apologies in advance if this breaks a style requirement.

This PR is an explicit variant of #303.

A Note

Thank you all for BayesianOptimization, it's a fantastic contribution!

Thanks,

Nandish Gupta
Data Science Engineer, SolasAI

[bwheelz36]

thanks, as noted on the pull request #319 I used #303 simply because it was submitted first.