DL之DNN：基于sklearn自带california_housing加利福尼亚房价数据集利用GD神经网络梯度下降算法进行回归预测(数据较多时采用mini-batch方式训练会更快)

目录

基于sklearn自带california_housing加利福尼亚房价数据集利用GD神经网络梯度下降算法进行回归预测(数据较多时采用mini-batch方式训练会更快)

输出结果

实现代码

基于sklearn自带california_housing加利福尼亚房价数据集利用GD神经网络梯度下降算法进行回归预测(数据较多时采用mini-batch方式训练会更快)

        该数据包含9个变量的20640个观测值，该数据集包含平均房屋价值作为目标变量和以下输入变量（特征）：平均收入、房屋平均年龄、平均房间、平均卧室、人口、平均占用、纬度和经度。

输出结果

epoch: 20 batch_id: 83 Batch loss 0.5640518069267273
……
epoch: 90 batch_id: 203 Batch loss 0.6403363943099976
epoch: 90 batch_id: 204 Batch loss 0.45315566658973694
epoch: 90 batch_id: 205 Batch loss 0.5528439879417419
epoch: 90 batch_id: 206 Batch loss 0.386596143245697

实现代码

import tensorflow as tf
import numpy as np 
from sklearn.datasets import fetch_california_housing 
from sklearn.preprocessing import StandardScaler 
 
scaler = StandardScaler()  将特征进行标准归一化
获取房价数据
housing = fetch_california_housing() 
m,n = housing.data.shape 
print (housing.keys())        输出房价的key
print (housing.feature_names) 输出房价的特征：
print (housing.target)  
print (housing.DESCR)  
 
 
housing_data_plus_bias = np.c_[np.ones((m,1)), housing.data] 
scaled_data = scaler. fit_transform(housing.data) 
data = np.c_[np.ones((m,1)),scaled_data] 
 
 T1、传统方式
 A = tf.placeholder(tf.float32,shape=(None,3)) 
 B = A + 5 
 with tf.Session() as sess: 
     test_b_l = B.eval(feed_dict={A:[[1,2,3]]}) 
     test_b_2 = B.eval(feed_dict={A:[[4,5,6],[7,8,9]]}) 
     print(test_b_1) 
     print(test_b_2) 
    
T2、采用mini-batch方式
X = tf.placeholder(tf.float32, shape=(None, n + 1), name="X") 
y = tf.placeholder(tf.float32, shape=(None, 1), name="y") 
采用optimizer计算梯度,设置参数
n_epochs = 100
learning_rate = 0.01 
batch_size=100
n_batches = int(np.ceil(m / batch_size)) 
theta = tf.Variable(tf.random_uniform([n + 1, 1], -1.0, 1.0, seed=42), name="theta")
y_pred = tf.matmul(X, theta, name="predictions") 
error = y_pred - y 
mse = tf.reduce_mean(tf.square(error), name="mse") 
optimizer = tf.train.GradientDescentOptimizer(learning_rate=learning_rate) 
training_op = optimizer.minimize(mse) 
init = tf.global_variables_initializer() 
 
定义mini-batch取数据方式
def fetch_batch(epoch, batch_index, batch_size): 
    np.random.seed(epoch * n_batches + batch_index) 
    indices = np.random.randint(m, size=batch_size)
    X_batch  = data[indices] 
    y_batch = housing.target.reshape(-1, 1)[indices] 
    return X_batch, y_batch
mini-batch计算过程
with tf.Session() as sess: 
    sess.run(init) 
    for epoch in range(n_epochs):/gfeMat 
        avg_cost = 0. 
        for batch_index in range(n_batches): 
            X_batch, y_batch = fetch_batch(epoch, batch_index, batch_size) 
            sess.run(training_op, feed_dict={X: X_batch, y: y_batch}) 
            
            if epoch % 10 == 0: 
                total_loss = 0 
                acc_train = mse.eval(feed_dict={X: X_batch, y: y_batch}) 
                total_loss += acc_train 
                print(acc_train, total_loss)
                print("epoch:",epoch, "batch_id:",batch_index, "Batch loss", total_loss)