python keras使用CGAN网络生成不同类型的时间序列并保存代码

下面是一个使用CGAN网络生成不同类型时间序列的示例代码，包括保存模型和生成的时间序列。

首先，我们需要导入必要的库：

from keras.layers import Input, Dense, Reshape, Flatten, Dropout, Embedding, multiply
from keras.layers import BatchNormalization, Activation, ZeroPadding2D, Concatenate, Conv2DTranspose
from keras.layers.advanced_activations import LeakyReLU
from keras.layers.convolutional import UpSampling2D, Conv2D
from keras.models import Sequential, Model
from keras.optimizers import Adam
from keras.utils import to_categorical
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

然后定义一些超参数：

img_rows = 28
img_cols = 28
channels = 1
img_shape = (img_rows, img_cols, channels)
latent_dim = 100
num_classes = 10

接下来，我们定义生成器和判别器模型：

def build_generator():

    model = Sequential()

    model.add(Dense(256, input_dim=latent_dim))
    model.add(LeakyReLU(alpha=0.2))
    model.add(BatchNormalization(momentum=0.8))
    model.add(Dense(512))
    model.add(LeakyReLU(alpha=0.2))
    model.add(BatchNormalization(momentum=0.8))
    model.add(Dense(1024))
    model.add(LeakyReLU(alpha=0.2))
    model.add(BatchNormalization(momentum=0.8))
    model.add(Dense(np.prod(img_shape), activation='tanh'))
    model.add(Reshape(img_shape))

    noise = Input(shape=(latent_dim,))
    label = Input(shape=(1,), dtype='int32')
    label_embedding = Flatten()(Embedding(num_classes, latent_dim)(label))

    model_input = multiply([noise, label_embedding])
    img = model(model_input)

    return Model([noise, label], img)


def build_discriminator():

    model = Sequential()

    model.add(Dense(512, input_dim=np.prod(img_shape)))
    model.add(LeakyReLU(alpha=0.2))
    model.add(Dense(512))
    model.add(LeakyReLU(alpha=0.2))
    model.add(Dropout(0.4))
    model.add(Dense(512))
    model.add(LeakyReLU(alpha=0.2))
    model.add(Dropout(0.4))
    model.add(Dense(1, activation='sigmoid'))

    img = Input(shape=img_shape)
    label = Input(shape=(1,), dtype='int32')
    label_embedding = Flatten()(Embedding(num_classes, np.prod(img_shape))(label))

    flat_img = Flatten()(img)
    model_input = multiply([flat_img, label_embedding])
    validity = model(model_input)

    return Model([img, label], validity)

然后，我们构建CGAN模型：

optimizer = Adam(0.0002, 0.5)

# Build and compile the discriminator
discriminator = build_discriminator()
discriminator.compile(loss='binary_crossentropy',
                      optimizer=optimizer,
                      metrics=['accuracy'])

# Build the generator
generator = build_generator()

# The generator takes noise and the target label as input
# and generates the corresponding digit of that label
noise = Input(shape=(latent_dim,))
label = Input(shape=(1,))
img = generator([noise, label])

# For the combined model we will only train the generator
discriminator.trainable = False

# The discriminator takes generated image and the target label as input
# and determines if the generated image is real or fake
valid = discriminator([img, label])

# The combined model  (stacked generator and discriminator)
# Trains the generator to fool the discriminator
combined = Model([noise, label], valid)
combined.compile(loss='binary_crossentropy', optimizer=optimizer)

接下来，我们加载数据集：

(X_train, y_train), (_, _) = mnist.load_data()

# Rescale -1 to 1
X_train = X_train / 127.5 - 1.
X_train = np.expand_dims(X_train, axis=3)

# Convert labels to one-hot encoding
y_train = to_categorical(y_train, num_classes=num_classes)

现在，我们定义一些辅助函数来保存模型和生成的时间序列：

def save_models(epoch):
    generator.save('cgan_generator_epoch_%d.h5' % epoch)
    discriminator.save('cgan_discriminator_epoch_%d.h5' % epoch)


def generate_and_save_images(generator, epoch, noise):
    # Generate images from noise
    labels = np.arange(0, num_classes).reshape(-1, 1)
    gen_imgs = generator.predict([noise, labels])

    # Rescale images to 0-1
    gen_imgs = 0.5 * gen_imgs + 0.5

    # Plot images
    fig, axs = plt.subplots(num_classes, 1, figsize=(10, 10))
    cnt = 0
    for i in range(num_classes):
        axs[i].imshow(gen_imgs[cnt, :, :, 0], cmap='gray')
        axs[i].set_title("Digit: %d" % cnt)
        axs[i].axis('off')
        cnt += 1
    fig.savefig("cgan_generated_image_epoch_%d.png" % epoch)
    plt.close()

最后，我们训练CGAN模型并保存生成的时间序列：

epochs = 10000
batch_size = 32
save_interval = 1000

# Adversarial ground truths
valid = np.ones((batch_size, 1))
fake = np.zeros((batch_size, 1))

for epoch in range(epochs):

    # ---------------------
    #  Train Discriminator
    # ---------------------

    # Select a random batch of images and labels
    idx = np.random.randint(0, X_train.shape[0], batch_size)
    imgs, labels = X_train[idx], y_train[idx]

    # Generate a batch of fake images
    noise = np.random.normal(0, 1, (batch_size, latent_dim))
    gen_imgs = generator.predict([noise, labels])

    # Train the discriminator
    d_loss_real = discriminator.train_on_batch([imgs, labels], valid)
    d_loss_fake = discriminator.train_on_batch([gen_imgs, labels], fake)
    d_loss = 0.5 * np.add(d_loss_real, d_loss_fake)

    # ---------------------
    #  Train Generator
    # ---------------------

    # Generate a batch of noise
    noise = np.random.normal(0, 1, (batch_size, latent_dim))

    # Train the generator (to have the discriminator label samples as valid)
    g_loss = combined.train_on_batch([noise, labels], valid)

    # Plot the progress
    print("%d [D loss: %f, acc.: %.2f%%] [G loss: %f]" % (epoch, d_loss[0], 100 * d_loss[1], g_loss))

    # Save generated images and models at save intervals
    if epoch % save_interval == 0:
        save_models(epoch)
        generate_and_save_images(generator, epoch, noise)

这样，我们就可以生成多个数字类型的时间序列，并将模型和生成的时间序列保存在本地。