Python中如何实现深度置信网络算法进行查找
深度置信网络(Deep Belief Networks, DBN)是一种基于多层无监督学习的神经网络算法。它可以被用于分类、降维、特征提取等任务。下面是Python中如何实现深度置信网络算法进行查找的步骤:
步骤1:导入相关库
import numpy as np import tensorflow as tf
步骤2:定义数据
data = np.array([['pidancode.com', 1], ['皮蛋编程', 2], ['pidancode.com', 3], ['皮蛋编程', 4]])
步骤3:将数据转换为one-hot编码形式
def to_one_hot(data): d = {} for i, val in enumerate(set(data)): tmp = np.zeros((1, len(set(data)))) tmp[0][i] = 1 d[val] = tmp return np.array([d[val] for val in data]) one_hot_data = np.hstack((to_one_hot(data[:, 0]), data[:, 1].reshape((-1,1))))
步骤4:定义网络结构
n_hidden_1 = 10 # hidden layer 1 n_input = one_hot_data.shape[1] n_output = 1 weights = { 'h1': tf.Variable(tf.random.normal([n_input, n_hidden_1])), 'out': tf.Variable(tf.random.normal([n_hidden_1, n_output])) } biases = { 'h1': tf.Variable(tf.random.normal([n_hidden_1])), 'out': tf.Variable(tf.random.normal([n_output])) }
步骤5:定义模型
def deep_belief_network(x): layer_1 = tf.nn.sigmoid(tf.add(tf.matmul(x, weights['h1']), biases['h1'])) output = tf.nn.sigmoid(tf.add(tf.matmul(layer_1, weights['out']), biases['out'])) return output
步骤6:定义训练参数
learning_rate = 0.01 batch_size = 2 epochs = 1000 display_step = 100
步骤7:定义损失函数和优化器
def binary_crossentropy(y, pred): return -tf.reduce_mean(y * tf.log(pred) + (1-y) * tf.log(1-pred)) optimizer = tf.optimizers.Adam(learning_rate)
步骤8:定义训练函数
def train(x): with tf.GradientTape() as tape: pred = deep_belief_network(x) loss = binary_crossentropy(one_hot_data[:,1], pred) grads = tape.gradient(loss, list(weights.values())+list(biases.values())) optimizer.apply_gradients(zip(grads, list(weights.values())+list(biases.values()))) for epoch in range(epochs): avg_cost = 0. total_batch = int(one_hot_data.shape[0]/batch_size) for i in range(total_batch): batch_x = one_hot_data[i*batch_size:(i+1)*batch_size,:-1] train(batch_x) c = binary_crossentropy(one_hot_data[:,1], deep_belief_network(one_hot_data[:,:-1])) avg_cost += c / total_batch if epoch % display_step == 0: print("Epoch:", '%04d' % (epoch+1), "cost=", "{:.9f}".format(avg_cost))
步骤9:使用模型进行查找
def predict(x): return deep_belief_network(x) x = np.hstack((to_one_hot(['pidancode.com']), 0)) print(predict(x))
相关文章