估算张量(Tensor.eval)与执行操作(Operation.run)

import tensorflow as tf
#创建数据流图：y = Wx + b,其中，W和B为存储节点，x为数据节点
x = tf.placeholder(tf.float32)
W = tf.Variable(1.0)
b = tf.Variable(1.0)
y = Wx + b
with tf.Session() as sess:
tf.global_variables_initializer().run() #Operation.run
fetch = y.eval(feed_dict = {x:3.0}) #Tensor.eval
print(fetch)Tensor.eval #fetch = 1.0*3.0+1