如何解决高斯过程wrt特征的偏导数
给出具有多维特征和标量观测值的高斯过程模型,如何在GPyTorch或GPFlow(或scikit-learn)中计算每个输入的输出wrt的导数?
解决方法
如果我正确理解了您的问题,则以下内容应该会为您提供使用TensorFlow在GPflow中的需求:
import numpy as np
import tensorflow as tf
import gpflow
### Set up toy data & model -- change as appropriate:
X = np.linspace(0,10,5)[:,None]
Y = np.random.randn(5,1)
data = (X,Y)
kernel = gpflow.kernels.SquaredExponential()
model = gpflow.models.GPR(data,kernel)
Xtest = np.linspace(-1,11,7)[:,None] # where you want to predict
### Compute gradient of prediction with respect to input:
# TensorFlow can only compute gradients with respect to tensor objects,# so let's convert the inputs to a tensor:
Xtest_tensor = tf.convert_to_tensor(Xtest)
with tf.GradientTape(
persistent=True # this allows us to compute different gradients below
) as tape:
# By default,only Variables are watched. For gradients with respect to tensors,# we need to explicitly watch them:
tape.watch(Xtest_tensor)
mean,var = model.predict_f(Xtest_tensor) # or any other predict function
grad_mean = tape.gradient(mean,Xtest_tensor)
grad_var = tape.gradient(var,Xtest_tensor)
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