diff --git a/experiment-1-1.py b/experiment-1-1.py deleted file mode 100644 index e69de29..0000000 diff --git a/experiment-1-2.py b/experiment-1-2.py deleted file mode 100644 index e69de29..0000000 diff --git a/experiment-1-3.py b/experiment-1-3.py deleted file mode 100644 index e69de29..0000000 diff --git a/experiment-1.py b/experiment-1.py new file mode 100644 index 0000000..359efdd --- /dev/null +++ b/experiment-1.py @@ -0,0 +1,250 @@ +import numpy as np +import matplotlib.pyplot as plt +from torchvision import datasets +import os + + +class MLP: + def __init__(self, input_size, hidden_size1, hidden_size2, output_size, weight_scale): + # initializes weights and biases for each layer + self.has_hidden_layer2 = hidden_size2 > 0 + + # for 0 or 1 hidden layer: + self.W1 = np.random.randn(input_size, hidden_size1) * weight_scale + self.b1 = np.zeros((1, hidden_size1)) + + if self.has_hidden_layer2: + self.W2 = np.random.randn(hidden_size1, hidden_size2) * weight_scale + self.b2 = np.zeros((1, hidden_size2)) + + # output layer + self.W3 = np.random.randn(hidden_size2 if self.has_hidden_layer2 else hidden_size1, output_size) * weight_scale + self.b3 = np.zeros((1, output_size)) + + def forward(self, x): + # Forward pass through the network + self.x = x # input for backpropagation + self.z1 = x @ self.W1 + self.b1 # Linear transformation for first layer + self.a1 = self.relu(self.z1) # ReLU activation + + if self.has_hidden_layer2: + self.z2 = self.a1 @ self.W2 + self.b2 # Linear transformation for second layer + self.a2 = self.relu(self.z2) # ReLU activation + self.z3 = self.a2 @ self.W3 + self.b3 # Linear transformation for output layer + else: + self.z3 = self.a1 @ self.W3 + self.b3 # No second layer, directly to output + + self.a3 = self.softmax(self.z3) # Softmax to get class probabilities + return self.a3 + + def backward(self, y, lr): + # Backward pass for weight updates using gradient descent + m = y.shape[0] + y_one_hot = self.one_hot_encode(y, self.W3.shape[1]) # Converts labels to one-hot encoding + + # Gradient for output layer + dz3 = self.a3 - y_one_hot + dw3 = (self.a2.T if self.has_hidden_layer2 else self.a1.T) @ dz3 / m + db3 = np.sum(dz3, axis=0, keepdims=True) / m + + if self.has_hidden_layer2: + dz2 = (dz3 @ self.W3.T) * self.relu_deriv(self.z2) # Gradient for second hidden layer + dw2 = (self.a1.T @ dz2) / m + db2 = np.sum(dz2, axis=0, keepdims=True) / m + dz1 = (dz2 @ self.W2.T) * self.relu_deriv(self.z1) # Gradient for first hidden layer + else: + dz1 = (dz3 @ self.W3.T) * self.relu_deriv(self.z1) # No second hidden layer + + dw1 = (self.x.T @ dz1) / m + db1 = np.sum(dz1, axis=0, keepdims=True) / m + + # Update weights and biases using gradient descent + self.W3 -= lr * dw3 + self.b3 -= lr * db3 + if self.has_hidden_layer2: + self.W2 -= lr * dw2 + self.b2 -= lr * db2 + self.W1 -= lr * dw1 + self.b1 -= lr * db1 + + @staticmethod + def relu(x): + # ReLU activation + return np.maximum(0, x) + + @staticmethod + def relu_deriv(x): + # derivation of ReLU activation for backpropagation + return (x > 0).astype(float) + + @staticmethod + def softmax(x): + # softmax function normalizes outputs to probabilities + e_x = np.exp(x - np.max(x, axis=1, keepdims=True)) # exponentiates inputs + return e_x / np.sum(e_x, axis=1, keepdims=True) # normalizes to get probabilities + + @staticmethod + def one_hot_encode(y, num_classes): + # converts labels to one-hot encoded format + return np.eye(num_classes)[y] + + @staticmethod + def cross_entropy_loss(y, y_hat): + # computes cross-entropy loss between true labels and predicted probabilities + m = y.shape[0] + m = y.shape[0] + eps = 1e-12 + y_hat_clipped = np.clip(y_hat, eps, 1. - eps) + log_probs = -np.log(y_hat_clipped[np.arange(m), y]) + return np.mean(log_probs) + + def fit(self, x_train, y_train, x_val, y_val, lr, epochs, batch_size, number): + train_losses = [] + val_accuracies = [] + + for epoch in range(1, epochs + 1): + perm = np.random.permutation(x_train.shape[0]) # Shuffle the training data + x_train_shuffled, y_train_shuffled = x_train[perm], y_train[perm] + + epoch_loss = 0.0 + num_batches = int(np.ceil(x_train.shape[0] / batch_size)) + + for i in range(num_batches): + start = i * batch_size + end = start + batch_size + x_batch = x_train_shuffled[start:end] # batch of inputs + y_batch = y_train_shuffled[start:end] # batch of labels + + # Forward pass, backward pass, and weight update + self.forward(x_batch) + self.backward(y_batch, lr) + + epoch_loss += self.cross_entropy_loss(y_batch, self.a3) # updating the epoch loss + + epoch_loss /= num_batches # average loss is defined + train_losses.append(epoch_loss) + + val_pred = self.predict(x_val) + val_acc = np.mean(val_pred == y_val) + val_accuracies.append(val_acc) \ + + print(f"Epoch {epoch:02d} | Training Loss: {epoch_loss:.4f} | Value Accuracy: {val_acc:.4f}") + + self.plot_graph(train_losses, val_accuracies, number) + return val_accuracies[-1] + + def plot_graph(self, train_losses, val_accuracies, number): + if not os.path.exists('results'): + os.makedirs('results') # creates results director + + fig, ax1 = plt.subplots() # initializes the plot + + ax1.set_xlabel('Epochs') + ax1.set_ylabel('Training Loss', color='tab:blue') + ax1.plot(range(1, len(train_losses) + 1), train_losses, color='tab:blue', label='Training Loss') + ax1.tick_params(axis='y', labelcolor='tab:blue') # defines loss subplot + + ax2 = ax1.twinx() + ax2.set_ylabel('Validation Accuracy', color='tab:orange') + ax2.plot(range(1, len(val_accuracies) + 1), val_accuracies, color='tab:orange', label='Validation Accuracy') + ax2.tick_params(axis='y', labelcolor='tab:orange') # defines accuracy subplot + + plt.title('Training Loss and Validation Accuracy over Epochs') + + result_path = 'results/experiment-1-' + str(number) + '.png' # defines the file name + fig.savefig(result_path) + print(f"Graph saved to: {result_path}") + + def predict(self, x): # predicts class labels for the input data + probs = self.forward(x) # forwards pass to get probabilities + return np.argmax(probs, axis=1) # returns the class with highest probability + + +# acquiring the FashionMNIST dataset +train_set = datasets.FashionMNIST(root='.', train=True, download=True) +test_set = datasets.FashionMNIST(root='.', train=False, download=True) + +# preprocessing the data by flattening images and normalizing them. +x_train = train_set.data.numpy().reshape(-1, 28 * 28).astype(np.float32) / 255.0 +y_train = train_set.targets.numpy() + +x_test = test_set.data.numpy().reshape(-1, 28 * 28).astype(np.float32) / 255.0 +y_test = test_set.targets.numpy() + +# MLP initialization (no hidden layers) +mlp1 = MLP( + input_size=28 * 28, + hidden_size1=0, + hidden_size2=0, + output_size=10, + weight_scale=1e-2 +) + +# trains the model +mlp1.fit( + x_train=x_train, + y_train=y_train, + x_val=x_test, + y_val=y_test, + lr=1e-2, + epochs=10, + batch_size=256, + number = 1 +) + +# tests the model +test_pred1 = mlp1.predict(x_test) +test_acc1 = np.mean(test_pred1 == y_test) +print(f"\nFinal test accuracy: {test_acc1:.4f}") + +# MLP initialization (one hidden layer) +mlp2 = MLP( + input_size=28 * 28, + hidden_size1=256, + hidden_size2=0, + output_size=10, + weight_scale=1e-2 +) + +# trains the model +mlp2.fit( + x_train=x_train, + y_train=y_train, + x_val=x_test, + y_val=y_test, + lr=1e-2, + epochs=10, + batch_size=256, + number = 2 +) + +# tests the model +test_pred2 = mlp2.predict(x_test) +test_acc2 = np.mean(test_pred2 == y_test) +print(f"\nFinal test accuracy: {test_acc2:.4f}") + +# MLP initialization (two hidden layers) +mlp3 = MLP( + input_size=28 * 28, + hidden_size1=256, + hidden_size2=256, + output_size=10, + weight_scale=1e-2 +) + +# trains the model +mlp3.fit( + x_train=x_train, + y_train=y_train, + x_val=x_test, + y_val=y_test, + lr=1e-2, + epochs=10, + batch_size=256, + number = 3 +) + +# tests the model +test_pred3 = mlp3.predict(x_test) +test_acc3 = np.mean(test_pred3 == y_test) +print(f"\nFinal test accuracy: {test_acc3:.4f}") diff --git a/multilayer-perceptron.py b/multilayer-perceptron.py index a265217..90127f5 100644 --- a/multilayer-perceptron.py +++ b/multilayer-perceptron.py @@ -154,11 +154,11 @@ y_train = train_set.targets.numpy() x_test = test_set.data.numpy().reshape(-1, 28 * 28).astype(np.float32) / 255.0 y_test = test_set.targets.numpy() -# MLP Initialization +# MLP initialization mlp = MLP( input_size=28 * 28, - hidden_size1=128, - hidden_size2=64, + hidden_size1=256, + hidden_size2=256, output_size=10, weight_scale=1e-2 ) @@ -171,7 +171,7 @@ mlp.fit( y_val=y_test, lr=1e-2, epochs=10, - batch_size=128 + batch_size=256 ) # 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