Merge pull request #2 from T-NIKHIL/main

Merging from T-NIKHIL fork

bo_output/test/surrogate_models.py

@@ -0,0 +1,95 @@
+# This file costructs surrogate models for the input datasets
+import numpy as np     
+import os
+import json
+from sklearn.model_selection import train_test_split
+from sklearn.metrics import mean_squared_error
+import math
+
+# Torch specific module imports
+import torch
+import gpytorch
+
+# botorch specific modules
+from botorch.fit import fit_gpytorch_model
+from botorch.models.gpytorch import GPyTorchModel
+
+# Plotting libraries
+import matplotlib as mpl
+import matplotlib.pyplot as plt
+
+# User defined python classes and files
+import utils_dataset as utilsd
+import input_class 
+import code_inputs as model_input
+
+np.random.seed(0)
+torch.manual_seed(0)
+
+device = "cuda" if torch.cuda.is_available() else "cpu"
+print(f"Using {device} device")
+
+# We will use the simplest form of GP model, exact inference
+class ExactGPModel(gpytorch.models.ExactGP,GPyTorchModel):
+    _num_outputs = 1  # to inform GPyTorchModel API
+    MIN_INFERRED_NOISE_LEVEL = 1e-5
+    def __init__(self, train_x, train_y, likelihood):
+        super(ExactGPModel, self).__init__(train_x, train_y, likelihood)
+        self.mean_module = gpytorch.means.ConstantMean()
+        if model_input.kernel=='RBF':
+            self.covar_module = gpytorch.kernels.ScaleKernel(gpytorch.kernels.RBFKernel())
+        elif model_input.kernel=='Matern':            
+            self.covar_module = gpytorch.kernels.ScaleKernel(gpytorch.kernels.MaternKernel(nu=0.5))
+
+    def forward(self, x):
+        mean_x = self.mean_module(x)
+        covar_x = self.covar_module(x)
+        return gpytorch.distributions.MultivariateNormal(mean_x, covar_x)
+
+#--------------------------- GP-0 ---------------------------#
+def train_surrogate_gp0(X_train,Y_train):
+
+    mse_gp0 = 0.0 
+    training_iter = model_input.epochs_GP0
+
+    # initialize likelihood and model
+    likelihood_gp0 = gpytorch.likelihoods.GaussianLikelihood()
+    model_gp0 = ExactGPModel(X_train, Y_train, likelihood_gp0) 
+
+    # Find optimal model hyperparameters
+    model_gp0.train()
+    likelihood_gp0.train()
+
+    # Use the adam optimizer
+    optimizer = torch.optim.Adam(model_gp0.parameters(), lr=model_input.learning_rate_gp0)  # Includes GaussianLikelihood parameters
+
+    # "Loss" for GPs - the marginal log likelihood
+    mll = gpytorch.mlls.ExactMarginalLogLikelihood(likelihood_gp0, model_gp0)
+
+    for i in range(training_iter):
+        optimizer.zero_grad()        # Zero gradients from previous iteration
+        output = model_gp0(X_train)  # Output from model
+        loss = -mll(output, Y_train) # Calc loss and backprop gradients         
+        loss.backward()
+        optimizer.step()
+
+    return model_gp0, likelihood_gp0
+
+def predict_surrogates(model, likelihood, X):
+
+    # Get into evaluation (predictive posterior) mode
+    model.eval()
+    likelihood.eval()
+
+    # Make predictions by feeding model through likelihood
+    with torch.no_grad(), gpytorch.settings.fast_pred_var():
+        prediction = model(X)
+        prediction = likelihood(model(X))
+
+    observed_mean = prediction.mean
+    observed_var = prediction.variance
+    observed_covar = prediction.covariance_matrix
+
+    return observed_mean, observed_var
+
+