def nesterov(nn, X_train, y_train, val_set=None, alpha=1e-3, mb_size=256, n_iter=2000, print_after=100): velocity = {k: np.zeros_like(v) for k, v in nn.model.items()} gamma = .9 minibatches = get_minibatch(X_train, y_train, mb_size) if val_set: X_val, y_val = val_set for iter in range(1, n_iter + 1): idx = np.random.randint(0, len(minibatches)) X_mini, y_mini = minibatches[idx] nn_ahead = copy.deepcopy(nn) nn_ahead.model.update({k: v + gamma * velocity[k] for k, v in nn.model.items()}) grad, loss = nn_ahead.train_step(X_mini, y_mini) if iter % print_after == 0: if val_set: val_acc = l.accuracy(y_val, nn.predict(X_val)) print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc)) else: print('Iter-{} loss: {:.4f}'.format(iter, loss)) for layer in grad: velocity[layer] = gamma * velocity[layer] + alpha * grad[layer] nn.model[layer] -= velocity[layer] return nn
def adam(nn, X_train, y_train, val_set=None, alpha=0.001, mb_size=256, n_iter=2000, print_after=100): M = {k: np.zeros_like(v) for k, v in nn.model.items()} R = {k: np.zeros_like(v) for k, v in nn.model.items()} beta1 = .9 beta2 = .999 minibatches = get_minibatch(X_train, y_train, mb_size) if val_set: X_val, y_val = val_set for iter in range(1, n_iter + 1): t = iter idx = np.random.randint(0, len(minibatches)) X_mini, y_mini = minibatches[idx] grad, loss = nn.train_step(X_mini, y_mini) if iter % print_after == 0: if val_set: val_acc = l.accuracy(y_val, nn.predict(X_val)) print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc)) else: print('Iter-{} loss: {:.4f}'.format(iter, loss)) for k in grad: M[k] = l.exp_running_avg(M[k], grad[k], beta1) R[k] = l.exp_running_avg(R[k], grad[k]**2, beta2) m_k_hat = M[k] / (1. - beta1**(t)) r_k_hat = R[k] / (1. - beta2**(t)) nn.model[k] -= alpha * m_k_hat / (np.sqrt(r_k_hat) + l.eps) return nn
def rmsprop(nn, X_train, y_train, val_set=None, alpha=1e-3, mb_size=256, n_iter=2000, print_after=100): cache = {k: np.zeros_like(v) for k, v in nn.model.items()} gamma = .9 minibatches = get_minibatch(X_train, y_train, mb_size) if val_set: X_val, y_val = val_set for iter in range(1, n_iter + 1): idx = np.random.randint(0, len(minibatches)) X_mini, y_mini = minibatches[idx] grad, loss = nn.train_step(X_mini, y_mini) if iter % print_after == 0: if val_set: val_acc = l.accuracy(y_val, nn.predict(X_val)) print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc)) else: print('Iter-{} loss: {:.4f}'.format(iter, loss)) for k in grad: cache[k] = l.exp_running_avg(cache[k], grad[k]**2, gamma) nn.model[k] -= alpha * grad[k] / (np.sqrt(cache[k]) + l.eps) return nn
def sgd(nn, X_train, y_train, val_set=None, alpha=1e-3, mb_size=256, n_iter=2000, print_after=100): minibatches = get_minibatch(X_train, y_train, mb_size) if val_set: X_val, y_val = val_set for iter in range(1, n_iter + 1): idx = np.random.randint(0, len(minibatches)) X_mini, y_mini = minibatches[idx] grad, loss = nn.train_step(X_mini, y_mini) if iter % print_after == 0: if val_set: val_acc = l.accuracy(y_val, nn.predict(X_val)) print('Iter-{} loss: {:.4f} validation: {:4f}'.format(iter, loss, val_acc)) else: print('Iter-{} loss: {:.4f}'.format(iter, loss)) for layer in grad: nn.model[layer] -= alpha * grad[layer] return nn