def normalize(X_train,X_test): mean = np.mean(X_train,axis=(0,1,2,3)) std = np.std(X_train, axis=(0, 1, 2, 3)) X_train = (X_train-mean)/(std+1e-7) X_test = (X_test-mean)/(std+1e-7) return X_train, X_test x_train, x_test = normalize(x_t
时间: 2023-06-17 17:04:22 浏览: 157
这是一个用于对训练集和测试集进行标准化处理的函数。它的目的是使数据在不同特征之间具有相同的尺度,以便于模型训练和预测。函数首先计算训练集的均值和标准差,然后对训练集和测试集分别进行标准化处理。最后返回标准化后的训练集和测试集。
具体来说,函数首先计算训练集的均值和标准差,这里使用了 numpy 库中的 mean 和 std 函数。axis 参数指定了计算的维度,这里是在每个通道上计算均值和标准差。然后,函数对训练集和测试集分别进行标准化处理,即将原始数据减去均值,再除以标准差。这里需要注意的是,为了避免分母为零,代码中加了一个小的常数 1e-7。最后,函数返回标准化后的训练集和测试集。
相关问题
def get_CIFAR10_data(num_training=5000, num_validation=500, num_test=500): cifar10_dir = r'D:\daima\cifar-10-python\cifar-10-batches-py' X_train, y_train, X_test, y_test = load_CIFAR10(cifar10_dir) print(X_train.shape) mask = range(num_training, num_training + num_validation) X_val = X_train[mask] y_val = y_train[mask] mask = range(num_training) X_train = X_train[mask] y_train = y_train[mask] mask = range(num_test) X_test = X_test[mask] y_test = y_test[mask] mean_image = np.mean(X_train, axis=0) X_train -= mean_image X_val -= mean_image X_test -= mean_image X_train = X_train.transpose(0, 3, 1, 2).copy() X_val = X_val.transpose(0, 3, 1, 2).copy() X_test = X_test.transpose(0, 3, 1, 2).copy() return { 'X_train': X_train, 'y_train': y_train, 'X_val': X_val, 'y_val': y_val, 'X_test': X_test, 'y_test': y_test, }这是一个加载cifar10数据集的函数,如何修改使其能加载mnist数据集,不使用使用 TensorFlow
要加载MNIST数据集,可以使用以下代码:
```
import numpy as np
import gzip
def load_mnist(path, kind='train'):
"""Load MNIST data from `path`"""
labels_path = f'{path}/{kind}-labels-idx1-ubyte.gz'
images_path = f'{path}/{kind}-images-idx3-ubyte.gz'
with gzip.open(labels_path, 'rb') as lbpath:
labels = np.frombuffer(lbpath.read(), dtype=np.uint8, offset=8)
with gzip.open(images_path, 'rb') as imgpath:
images = np.frombuffer(imgpath.read(), dtype=np.uint8, offset=16).reshape(len(labels), 784)
return images, labels
def get_MNIST_data(num_training=50000, num_validation=10000, num_test=10000):
mnist_dir = r'path/to/MNIST'
X_train, y_train = load_mnist(mnist_dir, kind='train')
X_test, y_test = load_mnist(mnist_dir, kind='t10k')
mask = range(num_training, num_training + num_validation)
X_val = X_train[mask]
y_val = y_train[mask]
mask = range(num_training)
X_train = X_train[mask]
y_train = y_train[mask]
mask = range(num_test)
X_test = X_test[mask]
y_test = y_test[mask]
# normalize images
mean_image = np.mean(X_train, axis=0)
X_train -= mean_image
X_val -= mean_image
X_test -= mean_image
# reshape images to 28x28x1
X_train = X_train.reshape(-1, 1, 28, 28)
X_val = X_val.reshape(-1, 1, 28, 28)
X_test = X_test.reshape(-1, 1, 28, 28)
return {
'X_train': X_train, 'y_train': y_train,
'X_val': X_val, 'y_val': y_val,
'X_test': X_test, 'y_test': y_test
}
```
其中 `load_mnist` 函数会从指定路径加载MNIST数据集,返回的 `images` 是一个形状为 `(num_samples, 784)` 的numpy数组,`labels`是一个形状为 `(num_samples,)` 的numpy数组。 `get_MNIST_data` 函数会调用 `load_mnist` 函数来加载数据集,并进行预处理,最后返回一个字典,包含训练集、验证集和测试集的图像和标签。
def get_CIFAR10_data(num_training=500, num_validation=50, num_test=50): """ Load the CIFAR-10 dataset from disk and perform preprocessing to prepare it for classifiers. These are the same steps as we used for the SVM, but condensed to a single function. """ # Load the raw CIFAR-10 data cifar10_dir = 'C:/download/cifar-10-python/cifar-10-batches-py/data_batch_1' X_train, y_train, X_test, y_test = load_CIFAR10(cifar10_dir) print (X_train.shape) # Subsample the data mask = range(num_training, num_training + num_validation) X_val = X_train[mask] y_val = y_train[mask] mask = range(num_training) X_train = X_train[mask] y_train = y_train[mask] mask = range(num_test) X_test = X_test[mask] y_test = y_test[mask] # Normalize the data: subtract the mean image mean_image = np.mean(X_train, axis=0) X_train -= mean_image X_val -= mean_image X_test -= mean_image # Transpose so that channels come first X_train = X_train.transpose(0, 3, 1, 2).copy() X_val = X_val.transpose(0, 3, 1, 2).copy() X_test = X_test.transpose(0, 3, 1, 2).copy() # Package data into a dictionary return { 'X_train': X_train, 'y_train': y_train, 'X_val': X_val, 'y_val': y_val, 'X_test': X_test, 'y_test': y_test, }
这段代码定义了一个函数get_CIFAR10_data,用于加载和预处理CIFAR-10数据集,并返回一个包含训练集、验证集和测试集的字典。
具体来说,这个函数完成了以下几个步骤:
1. 调用load_CIFAR10函数加载CIFAR-10数据集,得到原始的训练集和测试集数据(X_train, y_train, X_test, y_test)。
2. 对原始数据进行子采样,得到num_training个样本作为训练集,num_validation个样本作为验证集,num_test个样本作为测试集。
3. 对训练集、验证集和测试集进行均值归一化,即将每个像素减去训练集的均值像素值。这个操作可以提高模型的训练效果和泛化能力。
4. 对训练集、验证集和测试集进行通道转置,即将原来的(样本数, 高, 宽, 通道数)的四维数组转换为(样本数, 通道数, 高, 宽)的四维数组。这个操作是因为在深度学习中,通常把通道数放在第二个维度上,方便卷积计算。
5. 将处理后的训练集、验证集和测试集打包成一个字典,返回给调用者。
需要注意的是,这个函数中使用了load_CIFAR10函数,也就是另一个函数,用于从文件中加载CIFAR-10数据集。另外,这里的cifar10_dir变量指定了CIFAR-10数据集的路径,需要根据实际情况进行修改。
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