實驗前
import tensorflow as tf import numpy as np #create data x_data=np.random.rand(100).astype(np.float32)#訓練樣本 y_data=x_data*0.1+0.3#求參數(隱去真實參數和函數式)怎么知道樣本符合的這是線性函數呢?如果假設樣本符合的是二次函數呢?能求出參數值嗎? ###create tensorflow structure start### Weights = tf.Variable(tf.random_uniform([1],-1.0,1.0))#隨機參數初值 biases = tf.Variable(tf.zeros([1])) y=Weights*x_data+biases#按隨機參數擬合的y值一開始和y_data真值差很大 loss = tf.reduce_mean(tf.square(y-y_data))#損失值 optimizer = tf.train.GradientDescentOptimizer(0.5) ###create tensorflow structure end### train = optimizer.minimize(loss)#訓練 init = tf.initialize_all_variables()#初始化 sess = tf.Session() sess.run(init) for step in range(201): sess.run(train) if step % 20 == 0: print(step, sess.run(Weights), sess.run(biases))
實驗后:Weights、biases初始值為隨機值,但是隨着迭代它們會趨近於真值。條件為loss最小。
import tensorflow as tf import numpy as np #create data x_data=np.random.rand(100).astype(np.float32) y_data=x_data*0.1+0.3 ###create tensorflow structure start### Weights = tf.Variable(tf.random.uniform([1],-1.0,1.0)) biases = tf.Variable(tf.zeros([1])) y=Weights*x_data+biases loss = tf.reduce_mean(input_tensor=tf.square(y-y_data)) optimizer = tf.compat.v1.train.GradientDescentOptimizer(0.5) ###create tensorflow structure end### train = optimizer.minimize(loss) init = tf.compat.v1.initialize_all_variables() sess = tf.compat.v1.Session() sess.run(init) for step in range(201): sess.run(train) if step % 20 == 0: print(step, sess.run(Weights), sess.run(biases))
代碼對比可看出代碼前后的變化