def fit_and_plot_pytorch(wd): # 对权重参数衰减。权重名称一般是以weight结尾 net = nn.Linear(num_inputs, 1) nn.init.normal_(net.weight, mean=0, std=1) nn.init.normal_(net.bias, mean=0, std=1) optimizer_w = torch.optim.SGD(params=[net.weight], lr=lr, weight_decay=wd) # 对权重参数衰减 optimizer_b = torch.optim.SGD(params=[net.bias], lr=lr) # 不对偏差参数衰减 train_ls, test_ls = [], [] for _ in range(num_epochs): for X, y in train_iter: l = loss(net(X), y).mean() optimizer_w.zero_grad() optimizer_b.zero_grad() l.backward() # 对两个optimizer实例分别调用step函数,从而分别更新权重和偏差 optimizer_w.step() optimizer_b.step() train_ls.append(loss(net(train_features), train_labels).mean().item()) test_ls.append(loss(net(test_features), test_labels).mean().item()) d2l.semilogy(range(1, num_epochs + 1), train_ls, 'epochs', 'loss', range(1, num_epochs + 1), test_ls, ['train', 'test']) print('L2 norm of w:', net.weight.data.norm().item())
def train_and_pred(train_features, test_features, train_labels, test_data, num_epochs, lr, weight_decay, batch_size): net = get_net(train_features.shape[1]) train_ls, _ = train(net, train_features, train_labels, None, None, num_epochs, lr, weight_decay, batch_size) d2l.semilogy(range(1, num_epochs + 1), train_ls, 'epochs', 'rmse') print('train rmse %f' % train_ls[-1]) preds = net(test_features).detach().numpy() test_data['SalePrice'] = pd.Series(preds.reshape(1, -1)[0]) submission = pd.concat([test_data['Id'], test_data['SalePrice']], axis=1) submission.to_csv('./submission.csv', index=False)
def k_fold(k, X_train, y_train, num_epochs, learning_rate, weight_decay, batch_size): train_l_sum, valid_l_sum = 0, 0 for i in range(k): data = get_k_fold_data(k, i, X_train, y_train) net = get_net(X_train.shape[1]) train_ls, valid_ls = train(net, *data, num_epochs, learning_rate, weight_decay, batch_size) train_l_sum += train_ls[-1] valid_l_sum += valid_ls[-1] if i == 0: d2l.semilogy(range(1, num_epochs + 1), train_ls, 'epochs', 'rmse', range(1, num_epochs + 1), valid_ls, ['train', 'valid']) print('fold %d, train rmse %f, valid rmse %f' % (i, train_ls[-1], valid_ls[-1])) return train_l_sum / k, valid_l_sum / k
def fit_and_plot(lambd): w,b = init_params() train_ls,test_ls = [],[] for _ in range(num_epochs): for X,y in train_iter: ## 添加L2范数惩罚项 l = loss(net(X,w,b),y) + lambd *l2_penalty(w) l = l.sum() if w.grad is not None: w.grad.data.zero_() b.grad.data.zero_() l.backward() d2l.sgd([w,b],lr,batch_size) train_ls.append(loss(net(train_features,w,b),train_labels).mean().item()) test_ls.append(loss(net(test_features,w,b),test_labels).mean().item()) d2l.semilogy(range(1, num_epochs + 1), train_ls, 'epochs', 'loss', range(1, num_epochs + 1), test_ls, ['train', 'test']) print('L2 norm of w:',w.norm().item())