1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197
| import numpy as np from scipy.signal import welch from scipy.stats import entropy
class EEGCognitiveWorkloadExtractor: """ EEG认知负荷特征提取 基于Nature 2023论文实现 """ def __init__(self, fs: int = 256): self.fs = fs self.frequency_bands = { 'delta': (0.5, 4), 'theta': (4, 8), 'alpha': (8, 13), 'beta': (13, 30), 'gamma': (30, 45) } def extract_features(self, eeg_signal: np.ndarray) -> dict: """ 提取EEG特征 Args: eeg_signal: EEG信号 (channels, samples) Returns: features: { 'psd_bands': 各频段功率谱密度, 'entropy': 各通道熵值, 'asymmetry': 左右半球不对称性 } """ features = {} psd_features = self._extract_psd(eeg_signal) features['psd_bands'] = psd_features entropy_features = self._extract_entropy(eeg_signal) features['entropy'] = entropy_features asymmetry = self._calculate_asymmetry(eeg_signal) features['asymmetry'] = asymmetry return features def _extract_psd(self, signal: np.ndarray) -> dict: """提取各频段PSD""" psd_bands = {} for band_name, (low, high) in self.frequency_bands.items(): band_power = [] for channel in signal: freqs, psd = welch(channel, fs=self.fs, nperseg=256) band_mask = (freqs >= low) & (freqs <= high) band_power.append(np.sum(psd[band_mask])) psd_bands[band_name] = np.array(band_power) return psd_bands def _extract_entropy(self, signal: np.ndarray) -> np.ndarray: """提取信号熵值""" entropy_values = [] for channel in signal: freqs, psd = welch(channel, fs=self.fs) psd_normalized = psd / np.sum(psd) spectral_entropy = entropy(psd_normalized, base=2) entropy_values.append(spectral_entropy) return np.array(entropy_values) def _calculate_asymmetry(self, signal: np.ndarray) -> dict: """计算左右半球不对称性""" left_channels = signal[:7] right_channels = signal[7:] asymmetry = {} for band_name, (low, high) in self.frequency_bands.items(): left_power = [] right_power = [] for channel in left_channels: freqs, psd = welch(channel, fs=self.fs) band_mask = (freqs >= low) & (freqs <= high) left_power.append(np.sum(psd[band_mask])) for channel in right_channels: freqs, psd = welch(channel, fs=self.fs) band_mask = (freqs >= low) & (freqs <= high) right_power.append(np.sum(psd[band_mask])) asymmetry[band_name] = np.log(np.mean(left_power) / (np.mean(right_power) + 1e-10)) return asymmetry
class CognitiveWorkloadClassifier: """ 认知负荷分类器 低/中/高三级分类 """ def __init__(self): self.model = None self.feature_extractor = EEGCognitiveWorkloadExtractor() def train(self, eeg_data: np.ndarray, labels: np.ndarray): """ 训练分类器 Args: eeg_data: (N, channels, samples) labels: 'low', 'medium', 'high' """ from sklearn.svm import SVC from sklearn.preprocessing import StandardScaler features_list = [] for eeg in eeg_data: features = self.feature_extractor.extract_features(eeg) flat_features = [] for band_power in features['psd_bands'].values(): flat_features.extend(band_power) flat_features.extend(features['entropy']) for asym_val in features['asymmetry'].values(): flat_features.append(asym_val) features_list.append(flat_features) X = np.array(features_list) self.scaler = StandardScaler() X_scaled = self.scaler.fit_transform(X) self.model = SVC(kernel='rbf', C=1.0, gamma='scale') self.model.fit(X_scaled, labels) def predict(self, eeg_signal: np.ndarray) -> str: """ 预测认知负荷 Returns: workload_level: 'low' | 'medium' | 'high' """ features = self.feature_extractor.extract_features(eeg_signal) flat_features = [] for band_power in features['psd_bands'].values(): flat_features.extend(band_power) flat_features.extend(features['entropy']) for asym_val in features['asymmetry'].values(): flat_features.append(asym_val) X = np.array([flat_features]) X_scaled = self.scaler.transform(X) return self.model.predict(X_scaled)[0]
if __name__ == "__main__": np.random.seed(42) eeg_simulated = np.random.randn(14, 2560) eeg_simulated[0:7] += 0.5 * np.sin(2 * np.pi * 6 * np.arange(2560) / 256) extractor = EEGCognitiveWorkloadExtractor() features = extractor.extract_features(eeg_simulated) print("=== EEG特征提取结果 ===") print(f"Theta功率(左半球): {features['psd_bands']['theta'][:7].mean():.4f}") print(f"Theta功率(右半球): {features['psd_bands']['theta'][7:].mean():.4f}") print(f"Alpha不对称性: {features['asymmetry']['alpha']:.4f}") print(f"平均熵值: {features['entropy'].mean():.4f}")
|