我已经在R中实现了一个函数,用于估计基本sin函数的高斯过程参数。不幸的是,这个项目必须在Python中完成,我一直在尝试使用SKlearn在Python中复现R库的hetGP的行为,但我很难将前者映射到后者。
我对高斯过程的理解仍然有限,我对sklearn也是初学者,所以我真的很需要在这方面得到帮助。
我的R代码:
library(hetGP)
set.seed(123)
nvar <- 2
n <- 400
r <- 1
f <- function(x) sin(sum(x))
true_C <- matrix(1/8 * (3 + 2 * cos(2) - cos(4)), nrow = 2, ncol = 2)
design <- matrix(runif(nvar*n), ncol = nvar)
response <- apply(design, 1, f)
model <- mleHomGP(design, response, lower = rep(1e-4, nvar), upper = rep(1,nvar))
在代码稍后的部分,我使用了model$Ki
和model$theta
model$theta: 0.9396363 0.9669170
dim(model$ki): 400 400
迄今为止我的Python代码:
import numpy as np
from sklearn.gaussian_process import GaussianProcessRegressor
from sklearn.gaussian_process.kernels import RBF
n = 400
n_var = 2
real_c = np.full((2, 2), 1 / 8 * (3 + 2 * np.cos(2) - np.cos(4)))
design = np.random.uniform(size=n * n_var).reshape(-1, 2)
test = np.random.uniform(size=n * n_var).reshape(-1, 2)
response = np.apply_along_axis(lambda x: np.sin(np.sum(x)), 1, design)
kernel = RBF(length_scale=(1, 1))
gpr = GaussianProcessRegressor(kernel=kernel, n_restarts_optimizer=10,
optimizer="fmin_l_bfgs_b").fit(design, response)
gpr.predict(test, return_std=True)
theta = gpr.kernel_.get_params()["length_scale"]
#theta = gpr.kernel_.theta
k_inv = gpr._K_inv
theta = [1.78106558 1.80083585]