機器學習-tensorflow

例子1

先從helloworld開始: 

t@ubuntu:~$ python
Python 2.7.6 (default, Oct 26 2016, 20:30:19) 
[GCC 4.8.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 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(122) 
>>> print sess.run(a+b)
132

接下去兩個步驟：1，學python；2，看ts；

例子2

手寫數字識別，在ubuntu中安裝部署好環境；

代碼源自https://github.com/niektemme/tensorflow-mnist-predict

建立訓練用python代碼

# Copyright 2016 Niek Temme.
# Adapted form the on the MNIST biginners tutorial by Google. 
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================

"""A very simple MNIST classifier.
Documentation at
http://niektemme.com/ @@to do

This script is based on the Tensoflow MNIST beginners tutorial
See extensive documentation for the tutorial at
https://www.tensorflow.org/versions/master/tutorials/mnist/beginners/index.html
"""

#import modules
import tensorflow as tf
from tensorflow.examples.tutorials.mnist import input_data

#import data
mnist = input_data.read_data_sets("MNIST_data/", one_hot=True)

# Create the model
x = tf.placeholder(tf.float32, [None, 784])
W = tf.Variable(tf.zeros([784, 10]))
b = tf.Variable(tf.zeros([10]))
y = tf.nn.softmax(tf.matmul(x, W) + b)

# Define loss and optimizer
y_ = tf.placeholder(tf.float32, [None, 10])
cross_entropy = -tf.reduce_sum(y_*tf.log(y))
train_step = tf.train.GradientDescentOptimizer(0.01).minimize(cross_entropy)

# init_op = tf.global_variables_initializer() 看版本，使用該行仍是使用下面那行
init_op = tf.initialize_all_variables()
saver = tf.train.Saver()


# Train the model and save the model to disk as a model.ckpt file
# file is stored in the same directory as this python script is started
"""
The use of 'with tf.Session() as sess:' is taken from the Tensor flow documentation
on on saving and restoring variables.
https://www.tensorflow.org/versions/master/how_tos/variables/index.html
"""
with tf.Session() as sess:
    sess.run(init_op)
    for i in range(1000):
        batch_xs, batch_ys = mnist.train.next_batch(100)
        sess.run(train_step, feed_dict={x: batch_xs, y_: batch_ys})
        
    save_path = saver.save(sess, "/tmp/model.ckpt")
    print ("Model saved in file: ", save_path)

測試代碼

# Copyright 2016 Niek Temme. 
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================

"""Predict a handwritten integer (MNIST beginners).

Script requires
1) saved model (model.ckpt file) in the same location as the script is run from.
(requried a model created in the MNIST beginners tutorial)
2) one argument (png file location of a handwritten integer)

Documentation at:
http://niektemme.com/ @@to do
"""

#import modules
import sys
import tensorflow as tf
from PIL import Image,ImageFilter

def predictint(imvalue):
    """
    This function returns the predicted integer.
    The imput is the pixel values from the imageprepare() function.
    """
    
    # Define the model (same as when creating the model file)
    x = tf.placeholder(tf.float32, [None, 784])
    W = tf.Variable(tf.zeros([784, 10]))
    b = tf.Variable(tf.zeros([10]))
    y = tf.nn.softmax(tf.matmul(x, W) + b)

    init_op = tf.global_variables_initializer()
    saver = tf.train.Saver()
    
    """
    Load the model.ckpt file
    file is stored in the same directory as this python script is started
    Use the model to predict the integer. Integer is returend as list.

    Based on the documentatoin at
    https://www.tensorflow.org/versions/master/how_tos/variables/index.html
    """
    with tf.Session() as sess:
        sess.run(init_op)
        saver.restore(sess, "/tmp/model.ckpt")
        #print ("Model restored.")
   
        prediction=tf.argmax(y,1)
        return prediction.eval(feed_dict={x: [imvalue]}, session=sess)


def imageprepare(argv):
    """
    This function returns the pixel values.
    The imput is a png file location.
    """
    im = Image.open(argv).convert('L')
    width = float(im.size[0])
    height = float(im.size[1])
    newImage = Image.new('L', (28, 28), (255)) #creates white canvas of 28x28 pixels
    
    if width > height: #check which dimension is bigger
        #Width is bigger. Width becomes 20 pixels.
        nheight = int(round((20.0/width*height),0)) #resize height according to ratio width
        if (nheigth == 0): #rare case but minimum is 1 pixel
            nheigth = 1  
        # resize and sharpen
        img = im.resize((20,nheight), Image.ANTIALIAS).filter(ImageFilter.SHARPEN)
        wtop = int(round(((28 - nheight)/2),0)) #caculate horizontal pozition
        newImage.paste(img, (4, wtop)) #paste resized image on white canvas
    else:
        #Height is bigger. Heigth becomes 20 pixels. 
        nwidth = int(round((20.0/height*width),0)) #resize width according to ratio height
        if (nwidth == 0): #rare case but minimum is 1 pixel
            nwidth = 1
         # resize and sharpen
        img = im.resize((nwidth,20), Image.ANTIALIAS).filter(ImageFilter.SHARPEN)
        wleft = int(round(((28 - nwidth)/2),0)) #caculate vertical pozition
        newImage.paste(img, (wleft, 4)) #paste resized image on white canvas
    
    #newImage.save("sample.png")

    tv = list(newImage.getdata()) #get pixel values
    
    #normalize pixels to 0 and 1. 0 is pure white, 1 is pure black.
    tva = [ (255-x)*1.0/255.0 for x in tv] 
    return tva
    #print(tva)

def main(argv):
    """
    Main function.
    """
    imvalue = imageprepare(argv)
    predint = predictint(imvalue)
    print (predint[0]) #first value in list
    
if __name__ == "__main__":
    main(sys.argv[1])

運行結果：

矩陣-線性代數-http://www2.edu-edu.com.cn/lesson_crs78/self/j_0022/soft/ch0605.html

 

這本書不錯：超智能體https://yjango.gitbooks.io/superorganism/content/dai_ma_yan_shi_2.html