TensorFlow教程04：针对机器学习初学者的MNIST实验——源码和运行结果

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[小编推荐] 假定您已经安装好了TensorFlow，这里放了第一个MNIST实验的代码和参考结果，你可以直接运行验证。

源码

#!/usr/bin/pythonimport tensorflow as tfimport sysfrom tensorflow.examples.tutorials.mnist import input_datamnist = input_data.read_data_sets("MNIST_data/", one_hot=True)x = tf.placeholder("float", [None, 784])W = tf.Variable(tf.zeros([784,10]))b = tf.Variable(tf.zeros([10]))y = tf.nn.softmax(tf.matmul(x,W) + b)y_ = tf.placeholder("float", [None,10])cross_entropy = -tf.reduce_sum(y_*tf.log(y))train_step = tf.train.GradientDescentOptimizer(0.01).minimize(cross_entropy)init = tf.initialize_all_variables()sess = tf.Session()sess.run(init)for i in range(1000):  if i % 20 == 0:    sys.stdout.write('.')  batch_xs, batch_ys = mnist.train.next_batch(100)  sess.run(train_step, feed_dict={x: batch_xs, y_: batch_ys})print ""correct_prediction = tf.equal(tf.argmax(y,1), tf.argmax(y_,1))accuracy = tf.reduce_mean(tf.cast(correct_prediction, "float"))print sess.run(accuracy, feed_dict={x: mnist.test.images, y_: mnist.test.labels})

运行结果

Successfully downloaded train-images-idx3-ubyte.gz 9912422 bytes.Extracting MNIST_data/train-images-idx3-ubyte.gzSuccessfully downloaded train-labels-idx1-ubyte.gz 28881 bytes.Extracting MNIST_data/train-labels-idx1-ubyte.gzSuccessfully downloaded t10k-images-idx3-ubyte.gz 1648877 bytes.Extracting MNIST_data/t10k-images-idx3-ubyte.gzSuccessfully downloaded t10k-labels-idx1-ubyte.gz 4542 bytes.Extracting MNIST_data/t10k-labels-idx1-ubyte.gz..................................................0.9177

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