前言：
本文主要針對圖片格式的數字進行識別處理、建模和識別，在tensorflow叢集下執行。

程式碼：

-- coding: utf-8 --

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Spyder Editor

This is a temporasry script file.
MNIST TEST
Written by zhouguoxin on 2017-12-22
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from tensorflow.examples.tutorials.mnist import input_data
mnist = input_data.read_data_sets(“C:/Users/zhou8/.spyder-py3/MNIST_data”,one_hot=True)

import tensorflow as tf

輸入影象資料佔位符

x= tf.placeholder(tf.float32,[None,784])

計算權值和偏差

W = tf.Variable(tf.zeros([784,10]))
b = tf.Variable(tf.zeros([10]))

使用softmax模型

y= tf.nn.softmax(tf.matmul(x,W)+b)

代價函式佔位符

y_ = tf.placeholder(tf.float32,[None,10])

計算交叉熵評估代價

cross_entropy = tf.reduce_mean(-tf.reduce_sum(y_ * tf.log(y),reduction_indices=[1]))

使用梯度下降演算法優化：學習型速率為0.5

train_step = tf.train.GradientDescentOptimizer(0.5).minimize(cross_entropy)

build Session

sess = tf.InteractiveSession()

初始化變數

tf.global_variables_initializer().run()

訓練模型，訓練1000次

for _ in range(1000):
batch_xs,batch_ys = mnist.train.next_batch(100)
sess.run(train_step,feed_dict={x:batch_xs,y_:batch_ys})

calculate

correct_prediction = tf.equal(tf.argmax(y,1),tf.argmax(y_,1))

accuracy = tf.reduce_mean(tf.cast(correct_prediction,tf.float32))

print(“正確率：”,sess.run(accuracy,feed_dict={x:mnist.test.images,y_:mnist.test.labels}))