The Gaussian process regression can be computed in scikit learn using an object of class GaussianProcessRegressor as:
gp= GaussianProcessRegressor(alpha=1e-10, copy_X_train=True, kernel=1**2 + Matern(length_scale=2, nu=1.5) + WhiteKernel(noise_level=1), n_restarts_optimizer=0, normalize_y=False, optimizer='fmin_l_bfgs_b', random_state=None)
Here, we see that the L-BFGS-B algorithm has been used to optimize the hyperparameters. Is there any alternative (for example trust-region-reflective algorithm) to this algorithm available in sklearn?
EDIT: It provides some Constrained multivariate methods for optimization. Is there such functions available for other methods like trust-region-reflective algorithm and swarm intelligence (eg. Firefly algorithm)?