心电信号怎么用代码标记P波、T波、Q波、R波、S波

心电信号的波形标记通常使用心电图分析软件来完成，其标记方法基于一些特征点的自动检测和手动校正。以下是一个示例代码，演示如何使用Matlab的波形工具箱来标记心电信号的P波、T波、Q波、R波、S波：

% 读取心电信号数据
data = load('ecg_data.mat');
ecg = data.ecg_data;

% 滤波处理
fs = 1000; % 采样率
fc = 100; % 截止频率
[b, a] = butter(2, fc/(fs/2), 'high');
ecg_filtered = filtfilt(b, a, ecg);

% 心拍检测
[qrs_amp_raw, qrs_i_raw, delay] = pan_tompkin(ecg_filtered, fs, 0);

% 标记P波、T波、Q波、R波、S波
p_wave = zeros(size(ecg_filtered));
t_wave = zeros(size(ecg_filtered));
q_wave = zeros(size(ecg_filtered));
r_wave = zeros(size(ecg_filtered));
s_wave = zeros(size(ecg_filtered));

for i = 1:length(qrs_i_raw)
    qrs_i = qrs_i_raw(i);

    % 检测P波
    [~, p_i] = max(ecg_filtered(qrs_i-round(0.2*fs):qrs_i-round(0.03*fs)));
    p_wave(qrs_i-round(0.2*fs)+p_i-1) = ecg_filtered(qrs_i-round(0.2*fs)+p_i-1);
    
    % 检测T波
    [~, t_i] = max(ecg_filtered(qrs_i+round(0.03*fs):qrs_i+round(0.4*fs)));
    t_wave(qrs_i+round(0.03*fs)+t_i-1) = ecg_filtered(qrs_i+round(0.03*fs)+t_i-1);

    % 检测Q波和R波
    [~, r_i] = max(ecg_filtered(qrs_i-round(0.03*fs):qrs_i+round(0.03*fs)));
    q_wave(qrs_i-round(0.03*fs)+r_i-1) = ecg_filtered(qrs_i-round(0.03*fs)+r_i-1);
    r_wave(qrs_i-round(0.03*fs)+r_i-1) = ecg_filtered(qrs_i-round(0.03*fs)+r_i-1);

    % 检测S波
    [~, s_i] = min(ecg_filtered(qrs_i-round(0.03*fs):qrs_i+round(0.2*fs)));
    s_wave(qrs_i-round(0.03*fs)+s_i-1) = ecg_filtered(qrs_i-round(0.03*fs)+s_i-1);
end

% 绘制标记后的波形图
figure;
plot(ecg_filtered, 'k');
hold on;
plot(p_wave, 'g', 'LineWidth', 2);
plot(t_wave, 'b', 'LineWidth', 2);
plot(q_wave, 'r', 'LineWidth', 2);
plot(r_wave, 'm', 'LineWidth', 2);
plot(s_wave, 'c', 'LineWidth', 2);
legend({'ECG', 'P wave', 'T wave', 'Q wave', 'R wave', 'S wave'});
xlabel('Sample number');
ylabel('Amplitude');

此代码使用了Pan-Tompkins算法来检测心拍，然后根据心拍位置检测P波、T波、Q波、R波、S波，并使用不同的颜色来标记每个波形。