function data_preprocessing(data_type)
    if (strcmp(data_type, 'train'))
        if (isempty(dir(fullfile('./train_data/train_data_epoched/', ...
                '*.mat'))))
            %% 获取数据路径
            train_dir = dir(fullfile('./train_data/', '*.mat'));
            %% 获取idsNaN的数据路径
            data_idsNaN = dir(fullfile('./idsNaN/train_data/', '*.mat'));
            %% 数据预处理
            for i = 1:size(train_dir, 1)
                data_path = fullfile('./train_data', train_dir(i).name);
                idsNaN_path = fullfile('./idsNaN/train_data/', ...
                    data_idsNaN(i).name);
                save_path = fullfile('./train_data/train_data_epoched/',...
                    [train_dir(i).name(1:end-4), '_epoched.mat']);
                load(data_path, 'eeg_data', 'resTime');
                load(idsNaN_path, 'idsNaN');
                % 1-50Hz带通滤波
                eeg_data = my_eegfilter(eeg_data, 1, 50);
                % 划分trial
                epoched_eeg_data = epoch(eeg_data, idsNaN);
                save(save_path, 'epoched_eeg_data', 'resTime');
            end 
        end
    else
        if (isempty(dir(fullfile('./test_data/test_data_epoched/', ...
                '*.mat'))))
            %% 获取数据路径
            test_dir = dir(fullfile('./test_data/', '*.mat'));
            %% 获取idsNaN的数据路径
            data_idsNaN = dir(fullfile('./idsNaN/test_data/', '*.mat'));
            %% 数据预处理
            data_path = fullfile('./test_data', test_dir.name);
            idsNaN_path = fullfile('./idsNaN/test_data', data_idsNaN.name);
            save_path = fullfile('./test_data/test_data_epoched/',...
                [test_dir.name(1:end-4), '_epoched.mat']);
            load(data_path, 'eeg_data');
            load(idsNaN_path, 'idsNaN');
            % 1-50Hz带通滤波
            eeg_data = my_eegfilter(eeg_data, 1, 50);
            % 划分trial
            epoched_eeg_data = epoch(eeg_data, idsNaN);
            save(save_path, 'epoched_eeg_data'); 
        end
    end
end