【机器学习】回归问题实例（李宏毅老师作业1）

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任务介绍

1. 问题描述
   
   给出美国某一州过去3天的调查结果，然后预测第3天新检测阳性病例的百分比。

2. 数据相关特征feature

• States（34， encode to one-hot vectors） 34个州
• COVID-like illness（5） 新冠相似疾病
• behavior idicators（5）行为习惯
• belief indicators（2）信仰
• mental indicators （2）精神
• environment indicators （3）环境
• tested postive cases（1）新冠测试阳性分数

输入是34+18+18+17=87维，最后一列是我们需要去预测的

3. 文件数据说明：
   

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完成和调参

1. Some Utility Functions

def select_feat(train_data, valid_data, test_data, select_all=True):
    """ Selects useful features to perform regression
    :param train_data: 训练集
    :param valid_data: 验证集
    :param test_data:  测试集
    :param select_all: 是否选择全部feature 默认全部
    :return: x-特征属性，y-预测值
    """
    # y-最后一列 x-去掉最后一列
    y_train, y_valid = train_data[:, -1], valid_data[:, -1]
    raw_x_train, raw_x_valid, raw_x_test = train_data[:, :-1], valid_data[:, :-1], test_data

    if select_all:
        feat_idx = list(range(1, raw_x_train.shape[1]))
    else:
        # TODO: Select suitable feature columns.
        # StatesCOVIDPositive
        feat_idx = list(np.array([35, 36, 37, 47, 48, 52]))  # 1 day: COVIDPositive
        feat_idx += list(np.array([35, 36, 37, 47, 48, 52]) + 18)  # 2 day: COVIDPositive
        feat_idx += list(np.array([35, 36, 37, 47, 48]) + 36)  # 3 day: COVID
        feat_idx.sort()

    return raw_x_train[:, feat_idx], raw_x_valid[:, feat_idx], raw_x_test[:, feat_idx], y_train, y_valid


def same_seed(seed):
    """ Fixes random number generator seeds for reproducibility.
    :param seed: 确保每次的随机种子都相同
    """
    torch.backends.cudnn.deterministic = True
    torch.backends.cudnn.benchmark = False
    np.random.seed(seed)
    torch.manual_seed(seed)
    if torch.cuda.is_available():
        torch.cuda.manual_seed_all(seed)


def train_valid_split(data_set, valid_ratio, seed):
    """
    Split provided training data into training set and validation set
    :param data_set: 数据集
    :param valid_ratio: 验证集占总个数据集的比例
    :param seed: 随机种子
    :return:
    """
    valid_set_size = int(valid_ratio * len(data_set))
    train_set_size = len(data_set) - valid_set_size
    train_set, valid_set = random_split(data_set, [train_set_size, valid_set_size],
                                        generator=torch.Generator().manual_seed(seed))
    return np.array(train_set), np.array(valid_set)


def predict(test_loader, model, device):
    """
    进行预测
    :param test_loader: 测试数据集
    :param model: 模型
    :param device: gpu还是cpu
    :return:
    """
    model.eval()  # Set your model to evaluation mode.
    preds = []
    for x in tqdm(test_loader):
        x = x.to(device)
        with torch.no_grad():
            pred = model(x)
            preds.append(pred.detach().cpu())
    preds = torch.cat(preds, dim=0).numpy()
    # 保存好每次验证的结果
    save_pred(preds, os.path.join(config['result_path'], 'result.csv'))
    return preds


def save_pred(preds, file):
    ''' Save predictions to specified file '''
    with open(file, 'w') as fp:
        writer = csv.writer(fp)
        writer.writerow(['id', 'tested_positive'])
        for i, p in enumerate(preds):
            writer.writerow([i, p])

2. 网络模型和数据预处理

# 网络模型
class SimpleModel(nn.Module):
    def __init__(self, input_dim):
        super(SimpleModel, self).__init__()
        # TODO: modify model's structure, be aware of dimensions.
        self.layers = nn.Sequential(
            nn.Linear(input_dim, 16),
            nn.ReLU(),
            nn.Linear(16, 8),
            nn.ReLU(),
            nn.Linear(8, 1)
        )

    def forward(self, x):
        x = self.layers(x)
        x = x.squeeze(1)  # (B, 1) -> (B)
        return x


class COVID19Dataset(udata.Dataset):
    '''
    x: Features.
    y: Targets, if none, do prediction.
    '''

    def __init__(self, x, y=None):
        if y is None:
            self.y = y
        else:
            self.y = torch.FloatTensor(y)
        self.x = torch.FloatTensor(x)

    def __getitem__(self, idx):
        if self.y is None:
            return self.x[idx]
        else:
            return self.x[idx], self.y[idx]

    def __len__(self):
        return len(self.x)

3. train

def trainer(train_loader, valid_loader, model, config, device, loss_csv):
    criterion = nn.MSELoss(reduction='mean')  # Define your loss function, do not modify this.

    # Define your optimization algorithm.
    # TODO: Please check https://pytorch.org/docs/stable/optim.html to get more available algorithms.
    # TODO: L2 regularization (optimizer(weight decay...) or implement by your self).
    optimizer = torch.optim.SGD(model.parameters(), lr=config['learning_rate'], momentum=0.7)
    n_epochs, best_loss, step, early_stop_count = config['n_epochs'], math.inf, 0, 0

    for epoch in range(n_epochs):
        model.train()  # Set your model to train mode.
        loss_record = []

        # tqdm is a package to visualize your training progress.
        train_pbar = tqdm(train_loader, position=0, leave=True)

        for x, y in train_pbar:
            optimizer.zero_grad()  # Set gradient to zero.
            x, y = x.to(device), y.to(device)  # Move your data to device.
            pred = model(x)
            loss = criterion(pred, y)
            loss.backward()  # Compute gradient(backpropagation).
            optimizer.step()  # Update parameters.
            step += 1
            loss_record.append(loss.detach().item())

            # Display current epoch number and loss on tqdm progress bar.
            train_pbar.set_description(f'Epoch [{epoch + 1}/{n_epochs}]')
            train_pbar.set_postfix({'loss': loss.detach().item()})

        mean_train_loss = sum(loss_record) / len(loss_record)

        model.eval()  # Set your model to evaluation mode.
        loss_record = []
        for x, y in valid_loader:
            x, y = x.to(device), y.to(device)
            with torch.no_grad():
                pred = model(x)
                loss = criterion(pred, y)

            loss_record.append(loss.item())

        mean_valid_loss = sum(loss_record) / len(loss_record)
        print(f'Epoch [{epoch + 1}/{n_epochs}], Train loss: {mean_train_loss:.4f}, Valid loss: {mean_valid_loss:.4f}')
        loss_csv.write('Epoch [{:04d}/{:04d}], Train loss: {:.4f}, Valid loss: {:.4f}\n'.format(
            epoch + 1, n_epochs, mean_train_loss, mean_valid_loss))

        if mean_valid_loss < best_loss:
            best_loss = mean_valid_loss
            torch.save(model.state_dict(), config['model_path'])  # Save your best model
            print('Saving model with loss {:.3f}...'.format(best_loss))
            early_stop_count = 0
        else:
            early_stop_count += 1

        if early_stop_count >= config['early_stop']:
            print('\nModel is not improving, so we halt the training session.')
            return

4. main

def main():
    same_seed(config['seed'])  # 得到一个随机数种子
    # 创建文件夹
    if not os.path.exists(config['result_path']):
        os.makedirs(config['result_path'])
    # 创建需要保存的loss文件
    loss_csv = open(os.path.join(config['result_path'], 'loss.csv'), 'a+')
    loss_csv.write(
        "N_epochs:{}, Batch:{}, Init_lr:{}\n".format(config['n_epochs'], config['batch_size'], config['learning_rate']))
    # 读取训练集
    train_data, test_data = pd.read_csv('./data/covid_train.csv').values, pd.read_csv('./data/covid_test.csv').values
    # 把训练集分成 训练集+数据集
    train_data, valid_data = train_valid_split(train_data, config['valid_ratio'], config['seed'])
    # Print out the data size.
    print(f"""train_data size: {train_data.shape} 
    valid_data size: {valid_data.shape} 
    test_data size: {test_data.shape}""")
    # Select features
    x_train, x_valid, x_test, y_train, y_valid = select_feat(train_data, valid_data, test_data, config['select_all'])
    # Print out the number of features.
    print(f'number of features: {x_train.shape[1]}')
    loss_csv.write("Number of features:{} \n".format(x_train.shape[1]))
    train_dataset, valid_dataset, test_dataset = COVID19Dataset(x_train, y_train), \
                                                 COVID19Dataset(x_valid, y_valid), \
                                                 COVID19Dataset(x_test)
    # Pytorch data loader loads pytorch dataset into batches.
    train_loader = DataLoader(train_dataset, batch_size=config['batch_size'], shuffle=True, pin_memory=True)
    valid_loader = DataLoader(valid_dataset, batch_size=config['batch_size'], shuffle=False, pin_memory=True)
    test_loader = DataLoader(test_dataset, batch_size=config['batch_size'], shuffle=False, pin_memory=True)

    model = SimpleModel(input_dim=x_train.shape[1]).to(
        device)  # put your model and data on the same computation device.
    print('Parameters number is {}'.format(sum(param.numel() for param in model.parameters())))
    loss_csv.write('Parameters number is {} \n'.format(sum(param.numel() for param in model.parameters())))
    trainer(train_loader, valid_loader, model, config, device, loss_csv)
    predict(test_loader, model, device)
   
if __name__ == '__main__':
    main()
    print(torch.__version__)

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