代码
import tensorflow as tf
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))
pred = tf.nn.softmax(tf.matmul(x, w) + b)
cost = tf.reduce_mean(-tf.reduce_sum(y*tf.log(pred), reduction_indices=1))
optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost)
init = tf.global_variables_initializer()
with tf.Session() as sess:
sess.run(init)
for epoch in range(training_epochs):
avg_cost = 0
total_batch = int(mnist.train.num_examples/batch_size)
for i in range(total_batch):
xs, ys = mnist.train.next_batch(batch_size)
_,c = sess.run([optimizer, cost], feed_dict={x: xs, y:ys})
avg_cost += c/total_batch
if (epoch + 1) % display_step == 0:
print('epoch:', '%04d'%(epoch+1),'cost:','{:.9f}'.format(avg_cost))
print('finished')
correct_prediction = tf.equal(tf.argmax(pred, 1), tf.argmax(y, 1))
accuracy = tf.reduce_mean(tf.cast(correct_prediction, tf.float32))
print("Accuracy:", accuracy.eval({x: mnist.test.images[:3000], y: mnist.test.labels[:3000]}))
总结
- tensorflow的交叉熵的写法
- pred应该是一个静态图,可以直接进行验证,eval,比pytorch灵活
- 声明输入变量占位符的形状,tf.Variable(tf.float32,[None, 784])