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一、相关教程
1.中文教程 https://tf.wiki/zh_hans/basic/models.html#model-layer
内容丰富而全面,好评100分
函数的功能介绍比较细致和全面
多层感知机分类
https://tf.wiki/zh_hans/basic/models.html#model-layer
- class MNISTLoader():
- def __init__(self):
- mnist = tf.keras.datasets.mnist
- (self.train_data, self.train_label), (self.test_data, self.test_label) = mnist.load_data()
- # MNIST中的图像默认为uint8(0-255的数字)。以下代码将其归一化到0-1之间的浮点数,并在最后增加一维作为颜色通道
- self.train_data = np.expand_dims(self.train_data.astype(np.float32) / 255.0, axis=-1) # [60000, 28, 28, 1]
- self.test_data = np.expand_dims(self.test_data.astype(np.float32) / 255.0, axis=-1) # [10000, 28, 28, 1]
- self.train_label = self.train_label.astype(np.int32) # [60000]
- self.test_label = self.test_label.astype(np.int32) # [10000]
- self.num_train_data, self.num_test_data = self.train_data.shape[0], self.test_data.shape[0]
-
-
- def get_batch(self, batch_size):
- # 从数据集中随机取出batch_size个元素并返回,随机划重点
- index = np.random.randint(0, self.num_train_data, batch_size)
- return self.train_data[index, :], self.train_label[index]
- class MLP(tf.keras.Model):
- def __init__(self):
- super().__init__()
- self.flatten = tf.keras.layers.Flatten() # Flatten层将除第一维(batch_size)以外的维度展平
- self.dense1 = tf.keras.layers.Dense(units=100, activation=tf.nn.relu)
- self.dense2 = tf.keras.layers.Dense(units=10)
-
-
- def call(self, inputs): # [batch_size, 28, 28, 1]
- x = self.flatten(inputs) # [batch_size, 784] 输入层
- x = self.dense1(x) # [batch_size, 100] 隐藏层
- x = self.dense2(x) # [batch_size, 10] 输出层
- output = tf.nn.softmax(x)
- return output
-
- num_epochs = 5#过5遍训练集
- batch_size = 50#一次迭代所使用的样本量,每次迭代更新一次网络结果的参数
-
- learning_rate = 0.001
- model = MLP()
- data_loader = MNISTLoader()
- optimizer = tf.keras.optimizers.Adam(learning_rate=learning_rate)
- #5遍训练集,所需要的迭代次数
- num_batches = int(data_loader.num_train_data // batch_size * num_epochs)
- for batch_index in range(num_batches):
- X, y = data_loader.get_batch(batch_size)
- with tf.GradientTape() as tape:
- y_pred = model(X)
- loss = tf.keras.losses.sparse_categorical_crossentropy(y_true=y, y_pred=y_pred)
- loss = tf.reduce_mean(loss)
- print("batch %d: loss %f" % (batch_index, loss.numpy()))
- grads = tape.gradient(loss, model.variables)
- optimizer.apply_gradients(grads_and_vars=zip(grads, model.variables))
- #交叉熵作为损失函数,具体公式可百度
- #loss = tf.keras.losses.sparse_categorical_crossentropy(y_true=y, y_pred=y_pred)
- sparse_categorical_accuracy = tf.keras.metrics.SparseCategoricalAccuracy()
- num_batches = int(data_loader.num_test_data // batch_size)
- for batch_index in range(num_batches):
- start_index, end_index = batch_index * batch_size, (batch_index + 1) * batch_size
- y_pred = model.predict(data_loader.test_data[start_index: end_index])
- sparse_categorical_accuracy.update_state(y_true=data_loader.test_label[start_index: end_index], y_pred=y_pred)
- print("test accuracy: %f" % sparse_categorical_accuracy.result())
2.预测房价 DNN https://www.cnblogs.com/ylxn/p/10170948.html
https://www.kaggle.com/zoupet/neural-network-model-for-house-prices-tensorflow
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