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python3.6 + tensorflow入門:三維點擬合平面

參考連結:

http://wiki.jikexueyuan.com/project/tensorflow-zh/get_started/introduction.html

程式碼:

# -*- coding: utf-8 -*-
"""
Created on Fri Dec 21 14:34:56 2018

@author: Administrator
"""

import tensorflow as tf
import numpy as np

# 使用 NumPy 生成假資料(phony data), 總共 100 個點.
x_data = np.float32(np.random.rand(2, 100)) # 隨機輸入
y_data = np.dot([0.100, 0.200], x_data) + 0.300

# 構造一個線性模型
# 
b = tf.Variable(tf.zeros([1]))
W = tf.Variable(tf.random_uniform([1, 2], -1.0, 1.0))
y = tf.matmul(W, x_data) + b

# 最小化方差
loss = tf.reduce_mean(tf.square(y - y_data))
optimizer = tf.train.GradientDescentOptimizer(0.5)
train = optimizer.minimize(loss)

# 初始化變數
init = tf.initialize_all_variables()

# 啟動圖 (graph)
sess = tf.Session()
sess.run(init)

# 擬合平面
for step in range(0, 201):
    sess.run(train)
    if step % 20 == 0:
        print (step, sess.run(W), sess.run(b))

# 得到最佳擬合結果 W: [[0.100  0.200]], b: [0.300]

結果:

0 [[ 0.91210413 -0.04129256]] [ 0.04484042]
20 [[ 0.28546557  0.23647967]] [ 0.19098906]
40 [[ 0.15442868  0.23037918]] [ 0.25790811]
60 [[ 0.11846238  0.21355666]] [ 0.28405273]
80 [[ 0.10667393  0.20536564]] [ 0.29399648]
100 [[ 0.10247139  0.20204933]] [ 0.29774484]
120 [[ 0.10092307  0.20077361]] [ 0.29915351]
140 [[ 0.10034581  0.20029087]] [ 0.29968235]
160 [[ 0.10012968  0.20010923]] [ 0.2998808]
180 [[ 0.10004867  0.200041  ]] [ 0.29995525]
200 [[ 0.10001829  0.20001541]] [ 0.2999832]

說明:

極客學院的程式碼是python2版的,如果使用python3以上版本,程式碼會報語法錯誤:

(1) print 語法錯誤:把要列印的內容放入()裡,即修改為 print()即可;

(2)xrange 未定義:修改為range即可;