tensorflow实验-线性回归

实验结果:

Epoch: 0050 cost= 1779611648.000 W= 21.1876 b= -1.94716
Epoch: 0100 cost= 1779628928.000 W= 21.1871 b= -28.8248
Epoch: 0150 cost= 1779607424.000 W= 21.1888 b= -56.0113
Epoch: 0200 cost= 1779576064.000 W= 21.1912 b= -83.3023
Epoch: 0250 cost= 1779540736.000 W= 21.1937 b= -110.634
Epoch: 0300 cost= 1779503872.000 W= 21.1963 b= -137.979
Epoch: 0350 cost= 1779466112.000 W= 21.199 b= -165.326
Epoch: 0400 cost= 1779427712.000 W= 21.2017 b= -192.666
Epoch: 0450 cost= 1779389184.000 W= 21.2044 b= -219.997
Epoch: 0500 cost= 1779350784.000 W= 21.2071 b= -247.317
Epoch: 0550 cost= 1779312128.000 W= 21.2099 b= -274.623
Epoch: 0600 cost= 1779273600.000 W= 21.2126 b= -301.916
Epoch: 0650 cost= 1779234944.000 W= 21.2153 b= -329.197
Epoch: 0700 cost= 1779196288.000 W= 21.2181 b= -356.462
Epoch: 0750 cost= 1779157888.000 W= 21.2208 b= -383.714
Epoch: 0800 cost= 1779119360.000 W= 21.2235 b= -410.952
Epoch: 0850 cost= 1779080832.000 W= 21.2262 b= -438.175
Epoch: 0900 cost= 1779042432.000 W= 21.229 b= -465.386
Epoch: 0950 cost= 1779004160.000 W= 21.2317 b= -492.58
Epoch: 1000 cost= 1778965760.000 W= 21.2344 b= -519.762
Optimization Finished!
Training cost= 1.77897e+09 W= 21.2344 b= -519.762 

#coding:utf-8
'''
    线性回归
                y=Wx+b
    其中W为权重，b为偏置,x 即为LotArea，y 即为SalePrice。

'''
from __future__ import print_function, division
import tensorflow as tf
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

# 读入数据
train = pd.read_csv("dataset/linear_regression.csv")
# 选取房屋面积小于１２０００的数据
train = train[train['LotArea'] < 12000]
train_X = train['LotArea'].values.reshape(-1, 1)
train_Y = train['SalePrice'].values.reshape(-1, 1)

n_samples = train_X.shape[0]
# 学习率
learning_rate = 2
# 迭代次数
training_epochs = 1000
# 每多少次输出一次迭代结果
display_step = 50

# 这个X和Y和上面的train_X,train_Y是不一样的，这里只是个占位符，
# 训练开始的时候需要“喂”(feed)数据给它
X = tf.placeholder(tf.float32)
Y = tf.placeholder(tf.float32)
# 定义模型参数
W = tf.Variable(np.random.randn(), name="weight", dtype=tf.float32)
b = tf.Variable(np.random.randn(), name="bias", dtype=tf.float32)

# 定义模型
pred = tf.add(tf.multiply(W, X), b)
# 定义损失函数
cost = tf.reduce_sum(tf.pow(pred-Y, 2)) / (2 * n_samples)
# 使用Adam算法，至于为什么不使用一般的梯度下降算法，一会说
optimizer = tf.train.AdamOptimizer(learning_rate).minimize(cost)

# 初始化所有变量
init = tf.initialize_all_variables()

# 训练开始
with tf.Session() as sess:
    sess.run(init)

    for epoch in range(training_epochs):
        for (x, y) in zip(train_X, train_Y):
            sess.run(optimizer, feed_dict={X: x, Y: y})

        if (epoch + 1) % display_step == 0:
            c = sess.run(cost, feed_dict={X: train_X, Y: train_Y})
            print("Epoch:", '%04d' % (epoch + 1), "cost=", "{:.3f}".format(c), "W=", sess.run(W), "b=", sess.run(b))

    print("Optimization Finished!")
    training_cost = sess.run(cost, feed_dict={X: train_X, Y: train_Y})
    print("Training cost=", training_cost, "W=", sess.run(W), "b=", sess.run(b), '\n')

    # 画图
    plt.plot(train_X, train_Y, 'ro', label="Original data")
    plt.plot(train_X, sess.run(W) * train_X + sess.run(b), label="Fitted line")
    plt.legend()
    plt.show()

dataset/linear_regression.csv

,LotArea,SalePrice
0,8450,208500
1,9600,181500
2,11250,223500
3,9550,140000
4,10084,307000
5,10382,200000
6,6120,129900
7,7420,118000
8,11200,129500
9,11924,345000
10,10652,279500

测试1
生成测试数据

for x in range(0,100):
    y = 3+3*x
    print ",".join([str(x),str(x),str(y)])

测试结果

Epoch: 0050 cost= 0.000 W= 3.0 b= 2.99642
Epoch: 0100 cost= 1087.274 W= 3.14082 b= -50.4254
Epoch: 0150 cost= 36.720 W= 3.15869 b= -12.0979
Epoch: 0200 cost= 376.034 W= 2.29296 b= 19.6809
Epoch: 0250 cost= 0.008 W= 3.00197 b= 2.79233
Epoch: 0300 cost= 1718.088 W= 4.19537 b= -103.558
Epoch: 0350 cost= 0.246 W= 2.98618 b= 4.2617
Epoch: 0400 cost= 32.799 W= 3.14644 b= -11.1574
Epoch: 0450 cost= 0.123 W= 2.99225 b= 3.82624
Epoch: 0500 cost= 0.000 W= 3.00001 b= 2.99951
Epoch: 0550 cost= 81.916 W= 3.11827 b= 9.48149
Epoch: 0600 cost= 0.000 W= 2.99996 b= 2.99695
Epoch: 0650 cost= 47.679 W= 3.16947 b= -13.8402
Epoch: 0700 cost= 0.070 W= 3.00629 b= 2.36031
Epoch: 0750 cost= 0.000 W= 3.00002 b= 2.99861
Epoch: 0800 cost= 1.976 W= 3.03423 b= -0.419249
Epoch: 0850 cost= 0.003 W= 2.99807 b= 3.15099
Epoch: 0900 cost= 0.001 W= 3.00133 b= 2.90672
Epoch: 0950 cost= 0.002 W= 2.9985 b= 3.1233
Epoch: 1000 cost= 0.000 W= 3.00005 b= 2.99974
Optimization Finished!
Training cost= 3.12927e-06 W= 3.00005 b= 2.99974 

参考资料
http://blog.youkuaiyun.com/u010099080/article/details/52894773