机器学习（3）-Tensorflow安装与测试

$ python
...
>>> import tensorflow as tf
>>> hello = tf.constant(‘Hello, TensorFlow!‘)
>>> sess = tf.Session()
>>> print(sess.run(hello))
Hello, TensorFlow!
>>> a = tf.constant(10)
>>> b = tf.constant(32)
>>> print(sess.run(a + b))
42
>>>

import tensorflow as tf
import numpy
import matplotlib.pyplot as plt
rng = numpy.random

learning_rate = 0.01
training_epochs = 1000
display_step = 50
#数据集x
train_X = numpy.asarray([3.3,4.4,5.5,7.997,5.654,.71,6.93,4.168,9.779,6.182,7.59,2.167,
                         7.042,10.791,5.313,9.27,3.1])
#数据集y
train_Y = numpy.asarray([1.7,2.76,3.366,2.596,2.53,1.221,1.694,1.573,3.465,1.65,2.09,
                         2.827,3.19,2.904,2.42,2.94,1.3])
n_samples = train_X.shape[0]
X = tf.placeholder("float")
Y = tf.placeholder("float")

W = tf.Variable(rng.randn(), name="weight")
b = tf.Variable(rng.randn(), name="bias")

pred = tf.add(tf.mul(X, W), b)

cost = tf.reduce_sum(tf.pow(pred-Y, 2))/(2*n_samples)

optimizer = tf.train.GradientDescentOptimizer(learning_rate).minimize(cost)

init = tf.initialize_all_variables()
with tf.Session() as sess:
    sess.run(init)

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

    print "优化完成!"
    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‘

    #可视化显示
    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()