class LinearRegression(Predictor):
def __init__(self):
self.weights = None
self.bias = None
self.batch_sampler = None
def train(self, train_x, train_y, nb_epochs = 1000, batch_size = 1000, lr = 0.1):
self.weights = np.random.randn(*(1, train_x.shape[1]))
self.bias = np.zeros((1, train_x.shape[1]))
self.batch_sampler = BatchSampler(batch_size)
for epoch in range(nb_epochs):
batch_x, batch_y = self.batch_sampler.sample(train_x, train_y)
y_hat = self.predict(batch_x)
cost = self.__compute_cost(y_hat, batch_y)
grad_w, grad_b = self.__compute_grad(batch_x, y_hat, batch_y)
self.weights = self.weights - lr*grad_w
self.bias = self.bias - lr*grad_b
print("Epoch: " + str(epoch))
print("Cost: " + str(cost))
print("Gradients (W, b): " + str(grad_w)+ ", " + str(grad_b))
print("Weights: " + str(self.weights) + ", " + str(self.bias))
def predict(self, test_x):
return self.weights * test_x + self.bias
def __compute_cost(self, y_hat, y):
return np.mean(np.fabs(y_hat**2 - y**2))
def __compute_grad(self, batch_x, y_hat, train_y):
grad_w = 2*np.mean((y_hat - train_y)*batch_x)
grad_b = 2*np.mean(y_hat - train_y)
return grad_w, grad_b
class LogisticRegression(Predictor):
def __init__(self):
super().__init__()
self.weights = None
self.bias = None
self.batch_sampler = None
self.metrics_tracker = MetricsTracker()
def train(self,
train_x,
train_y,
nb_epochs=1000,
batch_size=1000,
lr=0.1,
lambd=0.000):
self.weights = np.zeros(shape=(train_x.shape[0], 1))
self.bias = 0
self.batch_sampler = BatchSampler(batch_size)
costs = []
accuracies = []
for epoch in range(nb_epochs):
lr_decay = lr * (nb_epochs - epoch) / nb_epochs
batch_x, batch_y = self.batch_sampler.sample(train_x, train_y)
print("Shape batch_x: " + str(batch_x.shape))
print("Shape train_y: " + str(batch_y.shape))
y_hat = self.predict(batch_x)
cost = self.__compute_cost(y_hat, batch_y, lambd)
grad_w, grad_b = self.__compute_grad(batch_x, y_hat, batch_y,
lambd)
self.weights = self.weights - lr_decay * grad_w
self.bias = self.bias - lr_decay * grad_b
if epoch % 100 == 0:
prediction = self.predict(train_x) > 0.5
accuracy = self.metrics_tracker.accuracy(train_y, prediction)
print("Epoch: " + str(epoch))
print("Cost: " + str(cost))
print("Gradients (W, b): " + str(grad_w) + ", " + str(grad_b))
print("Weights: " + str(self.weights) + ", " + str(self.bias))
print("Accuracy: " + str(accuracy))
costs.append(cost)
accuracies.append(accuracy)
return accuracies, costs
def predict(self, X):
a = np.dot(self.weights.T, X) + self.bias
return self.__sigmoid(a)
def __compute_cost(self, y_hat, y, lambd):
eps = 10e-5
return -np.mean(y * np.log(y_hat + eps) +
(1 - y) * np.log(1 - y_hat + eps)
) + 0.5 * lambd * np.sum(self.weights**2)
def __compute_grad(self, X, y_hat, Y, lambd):
m = X.shape[1]
grad_w = (1 / m) * np.dot(X, (y_hat - Y).T) + lambd * self.weights
grad_b = (1 / m) * np.sum(y_hat - Y)
print("Shape grad_w: " + str(grad_w.shape))
print("Shape grad_b: " + str(grad_b.shape))
assert (grad_w.shape == self.weights.shape)
return grad_w, grad_b
def __sigmoid(self, a):
return 1 / (1 + np.exp(-a))
class MLP(Predictor):
def __init__(self, n_x, n_hidden_layers, neurons_per_layer, n_output, activations):
super().__init__()
self.initialize_parameters(n_x, n_hidden_layers, neurons_per_layer, n_output)
self.batch_sampler = None
self.activations = activations
self.act_dict = {"sigmoid": self.__sigmoid, "relu": self.__relu, "linear": self.__linear}
self.metrics_tracker = MetricsTracker()
self.n_layers = n_hidden_layers + 2
assert(len(activations) == n_hidden_layers + 1)
def train(self, train_x, train_y, nb_epochs = 1000, batch_size = 1000, lr = 0.1):
self.batch_sampler = BatchSampler(batch_size)
costs = []
accuracies = []
for epoch in range(nb_epochs):
lr_decay = lr * (nb_epochs - epoch)/nb_epochs
batch_x, batch_y = self.batch_sampler.sample(train_x, train_y)
print("Shape batch_x: " + str(batch_x.shape))
print("Shape train_y: " + str(batch_y.shape))
cost, y_hat = self.__forward_prop(batch_x, batch_y)
grad = self.__backward_prop(batch_x, batch_y, y_hat)
self.learning_update(grad, lr)
if epoch%100 == 0:
prediction = self.predict(train_x) > 0.5
accuracy = self.metrics_tracker.accuracy(train_y, prediction)
print("Epoch: " + str(epoch))
print("Cost: " + str(cost))
print("Gradients (W, b): " + str(grad_w)+ ", " + str(grad_b))
print("Weights: " + str(self.weights) + ", " + str(self.bias))
print("Accuracy: " + str(accuracy))
costs.append(cost)
accuracies.append(accuracy)
return accuracies, costs
def initialize_parameters(self, n_x, n_hidden_layers, neurons_per_layer, n_output):
assert(len(neurons_per_layer) == n_hidden_layers + 1)
W0 = np.random.rand(shape = (neurons_per_layer[0], n_x))
b0 = np.zeros(shape = (neurons_per_layer[0], 1))
self.weights = {"W0": W0, "b0": b0}
for i in range(n_hidden_layers):
Wi = np.random.rand(shape = (neurons_per_layer[i + 1], neurons_per_layer[i]))
bi = np.zeros(shape = ((neurons_per_layer[i + 1], 1)))
self.weights["W" + str(i+1)] = Wi
self.weights["b" + str(i+1)] = bi
W_output = np.random.rand(shape = (n_output, neurons_per_layer[n_hidden_layers - 1]))
b_output = np.zeros(shape = ((n_output, 1)))
self.weights["W" + str(n_hidden_layers+1)] = W_output
self.weights["b" + str(n_hidden_layers+1)] = b_output
def __sigmoid(self, x):
return 1 / (1 + np.exp(-x))
def __relu(self, x):
return np.max(0, x, axis=1)
def __linear(self, x):
return x
def __forward_prop(batch_x, batch_y):
A_last = batch_x
for i in range(self.n_layers):
Wi = self.weights["W" + str(i)]
bi = self.weights["b" + str(i)]
Z = Wi * A_last + bi
A_output = self.act_dict[self.activations[i]]
A_last = A_output
m = batch_x.shape[1]
eps = 10e-5
cost = (-1/m) * np.sum(Y * np.log(A_output + eps) + (1 - Y)*np.log(1 - A_output + eps))
assert(cost.shape == ())
assert(A_output.shape == (1, m))
cost = np.squeeze(cost)
return cost, A_output
def __backward_prop(batch_x, batch_y, y_hat):
def predict(self, X):
a = np.dot(self.weights.T, X) + self.bias
return self.__sigmoid(a)
def __compute_cost(self, y_hat, y, lambd):
eps = 10e-5
return - np.mean(y * np.log(y_hat + eps) + (1-y) * np.log(1 - y_hat + eps)) + 0.5*lambd*np.sum(self.weights**2)
def __compute_grad(self, X, y_hat, Y, lambd):
m = X.shape[1]
grad_w = (1/m) * np.dot(X, (y_hat - Y).T) + lambd * self.weights
grad_b = (1/m) * np.sum(y_hat - Y)
print("Shape grad_w: " + str(grad_w.shape))
print("Shape grad_b: " + str(grad_b.shape))
assert(grad_w.shape == self.weights.shape)
return grad_w, grad_b
