#如何建立神经网络的结构:层
import tensorflow as tf
import numpy as np
import matplotlib.pyplot as plt
def add_layer(inputs,in_size,out_size,activation_function=None):
Weights=tf.Variable(tf.random_normal([in_size,out_size]))
biases=tf.Variable(tf.zeros([1,out_size]))+0.1
Wx_plus_b=tf.matmul(inputs,Weights)+biases
if activation_function is None:
outputs=Wx_plus_b
else:
outputs=activation_function(Wx_plus_b)
return outputs
x_data=np.linspace(-1,1,300)[:,np.newaxis]
noise=np.random.normal(0,0.05,x_data.shape)
y_data=np.square(x_data)-0.5+noise
##用placeholder作为占位时,必须定义类型,因为没有默认类型
xs=tf.placeholder(tf.float32,[None,1])
ys=tf.placeholder(tf.float32,[None,1])
#定义隐藏层
l1=add_layer(xs,1,10,activation_function=tf.nn.relu)
prediction=add_layer(l1,10,1,activation_function=None)
loss=tf.reduce_mean(tf.reduce_sum(tf.square(ys-prediction),reduction_indices=[1]))
train_step=tf.train.GradientDescentOptimizer(0.1).minimize(loss)
init=tf.global_variables_initializer()
with tf.Session()as sess:
sess.run(init)
fig=plt.figure()
ax=fig.add_subplot(1,1,1)
ax.scatter(x_data,y_data)
plt.ion()#不暂停
plt.show()
for i in range(1000):
sess.run(train_step,feed_dict={xs:x_data,ys:y_data})
if i%50==0:
# print(sess.run(loss,feed_dict={xs:x_data,ys:y_data}))
prediction_value=sess.run(prediction,feed_dict={xs:x_data,ys:y_data})
# print(prediction_value)
plt.plot(x_data,prediction_value,'r',lw=5)
# ax.lines.remove(lines[0])
plt.pause(0.1)