TensorFlow softmax回归

最新推荐文章于 2023-02-26 20:11:38 发布

Neekity

最新推荐文章于 2023-02-26 20:11:38 发布

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分类专栏： tensorflow python 文章标签： python tensorflow

本文链接：https://blog.youkuaiyun.com/Neekity/article/details/85225927

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本文介绍了一个基于TensorFlow的简单神经网络模型，用于MNIST手写数字数据集的分类任务。模型使用了softmax回归，并通过梯度下降优化器进行训练。文章详细展示了如何加载MNIST数据集、构建神经网络、定义损失函数、执行训练过程以及评估模型准确性。

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tf.cast 是转换类型

from __future__ import print_function
import tensorflow as tf
import numpy as np
import matplotlib.pyplot as plt
from tensorflow.examples.tutorials.mnist import input_data
mnist=input_data.read_data_sets('/tmp/data/',one_hot=True)

learning_rate = 0.01
training_epochs=25
batch_size=100
display_step=1

x=tf.placeholder(tf.float32,[None,784])
y=tf.placeholder(tf.float32,[None,10])
W=tf.Variable(tf.zeros([784,10]))
b=tf.Variable(tf.zeros([10]))
predict=tf.nn.softmax(tf.matmul(x,W)+b)
loss=tf.reduce_mean(-tf.reduce_sum(y*tf.log(predict),reduction_indices=1))
optimizer=tf.train.GradientDescentOptimizer(learning_rate).minimize(loss)
init=tf.global_variables_initializer()
with tf.Session() as sess:
    sess.run(init)
    for epoch in range(training_epochs):
        avg_loss=0.
        total_batch=int(mnist.train.num_examples/batch_size)
        for i in range(total_batch):
            batch_xs, batch_ys=mnist.train.next_batch(batch_size)
            _, c =sess.run([optimizer,loss],feed_dict={x:batch_xs,y:batch_ys})
            avg_loss+=c/total_batch  
        print('Epoch:',epoch+1,'Loss:',avg_loss)  
    correct_pre=tf.equal(tf.argmax(predict,1),tf.argmax(y,1))
    accuracy=tf.reduce_mean(tf.cast(correct_pre,tf.float32))
    print('correct_pre:',correct_pre)
    print('Accuracy:',accuracy.eval({x:mnist.test.images,y:mnist.test.labels}))