Tensorflow中的placeholder和feed_dict的使用

tf.placeholder(dtype, shape=None, name=None)

import tensorflow as tf

x = tf.placeholder(tf.string)

with tf.Session() as sess:
  output = sess.run(x, feed_dict={x: 'Hello World'})
  print(output)

import tensorflow as tf

x = tf.placeholder(tf.string)
y = tf.placeholder(tf.int32)
z = tf.placeholder(tf.float32)

with tf.Session() as sess:
  output = sess.run(x, feed_dict = {x :'Hello World', y:123, z:45.67})
  print(output)
  output = sess.run(y, feed_dict = {x :'Hello World', y:123, z:45.67})
  print(output)
  output = sess.run(z, feed_dict = {x :'Hello World', y:123, z:45.67})
print(output)

import tensorflow as tf
import numpy as np

x = tf.placeholder(tf.float32, shape=(3, 3)) 
y = tf.matmul(x, x) 
 
with tf.Session() as sess:  
  rand_array = np.random.rand(3, 3)
print(sess.run(y, feed_dict = {x: rand_array}))