[~, idx] = max(test_labels, [], 2);解释

`max`函数用于找到矩阵每行或每列的最大值及其索引。在这里，`test_labels`是一个矩阵，其每一行对应一个样本的标签，每一列对应一个类别。

`[~, idx]`表示将`max`函数的第一个输出（即最大值）赋值给一个占位符，用波浪线`~`表示我们不需要这个输出，而第二个输出（即最大值的索引）赋值给变量`idx`。

`max(test_labels, [], 2)`表示在`test_labels`矩阵的每一行中找到最大值及其索引。第二个参数`[]`表示在矩阵列的维度上执行操作，即每一行中找到最大值及其索引。

因此，`[~, idx] = max(test_labels, [], 2);`的作用是找到`test_labels`矩阵每一行中最大值的索引，并将这些索引存储在变量`idx`中。

相关问题

iris = load('C:\Users\86187\Desktop\Iris (1).csv'); % 导入鸢尾花数据集 train_data = [meas(1:40,:); meas(51:90,:); meas(101:140,:)]; train_labels = [ones(40,1); 2*ones(40,1); 3*ones(40,1)]; test_data = [meas(41:50,:); meas(91:100,:); meas(141:150,:)]; test_labels = [ones(10,1); 2*ones(10,1); 3*ones(10,1)]; mu1 = mean(train_data(train_labels==1,:)); sigma1 = var(train_data(train_labels==1,:)); mu2 = mean(train_data(train_labels==2,:)); sigma2 = var(train_data(train_labels==2,:)); mu3 = mean(train_data(train_labels==3,:)); sigma3 = var(train_data(train_labels==3,:)); pred_labels = zeros(size(test_labels)); for i=1:size(test_data,1) p1 = normpdf(test_data(i,:), mu1, sqrt(sigma1)); p2 = normpdf(test_data(i,:), mu2, sqrt(sigma2)); p3 = normpdf(test_data(i,:), mu3, sqrt(sigma3)); [~, idx] = max([p1,p2,p3]); pred_labels(i) = idx; end tp = sum((test_labels==1) & (pred_labels==1)); fp = sum((test_labels~=1) & (pred_labels==1)); fn = sum((test_labels==1) & (pred_labels~=1)); precision1 = tp / (tp + fp); recall1 = tp / (tp + fn); f1_score1 = 2 * precision1 * recall1 / (precision1 + recall1); tp = sum((test_labels==2) & (pred_labels==2)); fp = sum((test_labels~=2) & (pred_labels==2)); fn = sum((test_labels==2) & (pred_labels~=2)); precision2 = tp / (tp + fp); recall2 = tp / (tp + fn); f1_score2 = 2 * precision2 * recall2 / (precision2 + recall2); tp = sum((test_labels==3) & (pred_labels==3)); fp = sum((test_labels~=3) & (pred_labels==3)); fn = sum((test_labels==3) & (pred_labels~=3)); precision3 = tp / (tp + fp); recall3 = tp / (tp + fn); f1_score3 = 2 * precision3 * recall3 / (precision3 + recall3);中函数或变量 'meas' 无法识别。 出错 Untitled (line 2) train_data = [meas(1:40,:); meas(51:90,:); meas(101:140,:)];怎么解决

这个错误通常是因为没有导入正确的数据文件导致的。在这个脚本中，没有看到导入数据的代码行。请确认您已经正确导入了名为"Iris (1).csv"的数据文件，并将其保存在'C:\Users\86187\Desktop\'路径下。如果数据文件的名称或路径不正确，那么您需要相应地修改代码行2和3。

另外，您可能需要使用内置的`csvread`或`readtable`函数来正确读取CSV文件，而不是使用`load`函数。请尝试以下代码来导入CSV数据：

data = readtable('C:\Users\86187\Desktop\Iris (1).csv');
meas = table2array(data(:,1:4));

这将把您的CSV数据文件读入一个表中，并将其转换为一个矩阵`meas`，其中包含所有的测量值。您可以根据需要修改代码以适应这个新的数据结构。

import os import pickle import cv2 import matplotlib.pyplot as plt import numpy as np from keras.layers import Conv2D, MaxPooling2D, Flatten, Dense, Dropout from keras.models import Sequential from keras.optimizers import adam_v2 from keras_preprocessing.image import ImageDataGenerator from sklearn.model_selection import train_test_split from sklearn.preprocessing import LabelEncoder, OneHotEncoder, LabelBinarizer def load_data(filename=r'/root/autodl-tmp/RML2016.10b.dat'): with open(r'/root/autodl-tmp/RML2016.10b.dat', 'rb') as p_f: Xd = pickle.load(p_f, encoding="latin-1") # 提取频谱图数据和标签 spectrograms = [] labels = [] train_idx = [] val_idx = [] test_idx = [] np.random.seed(2016) a = 0 for (mod, snr) in Xd: X_mod_snr = Xd[(mod, snr)] for i in range(X_mod_snr.shape[0]): data = X_mod_snr[i, 0] frequency_spectrum = np.fft.fft(data) power_spectrum = np.abs(frequency_spectrum) ** 2 spectrograms.append(power_spectrum) labels.append(mod) train_idx += list(np.random.choice(range(a * 6000, (a + 1) * 6000), size=3600, replace=False)) val_idx += list(np.random.choice(list(set(range(a * 6000, (a + 1) * 6000)) - set(train_idx)), size=1200, replace=False)) a += 1 # 数据预处理 # 1. 将频谱图的数值范围调整到0到1之间 spectrograms_normalized = spectrograms / np.max(spectrograms) # 2. 对标签进行独热编码 label_binarizer = LabelBinarizer() labels_encoded= label_binarizer.fit_transform(labels) # transfor the label form to one-hot # 3. 划分训练集、验证集和测试集 # X_train, X_temp, y_train, y_temp = train_test_split(spectrograms_normalized, labels_encoded, test_size=0.15, random_state=42) # X_val, X_test, y_val, y_test = train_test_split(X_temp, y_temp, test_size=0.5, random_state=42) spectrogramss = np.array(spectrograms_normalized) print(spectrogramss.shape) labels = np.array(labels) X = np.vstack(spectrogramss) n_examples = X.shape[0] test_idx = list(set(range(0, n_examples)) - set(train_idx) - set(val_idx)) np.random.shuffle(train_idx) np.random.shuffle(val_idx) np.random.shuffle(test_idx) X_train = X[train_idx] X_val = X[val_idx] X_test = X[test_idx] print(X_train.shape) print(X_val.shape) print(X_test.shape) y_train = labels[train_idx] y_val = labels[val_idx] y_test = labels[test_idx] print(y_train.shape) print(y_val.shape) print(y_test.shape) # X_train = np.expand_dims(X_train,axis=-1) # X_test = np.expand_dims(X_test,axis=-1) # print(X_train.shape) return (mod, snr), (X_train, y_train), (X_val, y_val), (X_test, y_test) 这是我的数据预处理代码

你的数据预处理代码看起来很完整。它首先加载pickle文件，然后提取频谱图数据和标签。接下来，它对频谱图数据进行归一化处理，并对标签进行独热编码。最后，它将数据集划分为训练集、验证集和测试集，并返回这些数据集。

在代码中，你还有一些注释掉的代码段，例如对数据集进行划分的部分。如果你打算使用这些划分代码，你可以取消注释相应的行。另外，如果你的频谱图数据维度是二维的，你可能需要使用`np.expand_dims`函数将其扩展为三维，以便与Conv2D层兼容。

如果你还有其他问题或需要进一步帮助，请随时问我。