DL之NN：利用(本地数据集50000张数据集)调用自定义神经网络network.py实现手写数字图片识别94%准确率

DL之NN：利用(本地数据集50000张数据集)调用自定义神经网络network.py实现手写数字图片识别94%准确率

目录

输出结果

代码设计

输出结果

更新……

代码设计

  

   

    

     

    
    

     

      import mnist_loader
     
    
   

    

     

    
    

     

      import network
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      training_data, validation_data, test_data = mnist_loader.load_data_wrapper()  
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      print("training_data")   
     
    
   

    

     

    
    

     

      print(type(training_data))
     
    
   

    

     

    
    

     

      print(list(training_data)) 
     
    
   

    

     

    
    

     

      print(training_data[0][0].shape)  
     
    
   

    

     

    
    

     

      print(training_data[0][1].shape)  
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      net = network.Network([784, 30, 10]) 
     
    
   

    

     

    
    

     

      net.SGD(training_data, 30, 10, 3.0, test_data=test_data)
     
    
  
 

  

   

    

     

    
    

     

      import random  
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      import numpy as np
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      class Network(object): 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def __init__(self, sizes): 
     
    
   

    

     

    
    

     

       """The list ``sizes`` contains the number of neurons in the
     
    
   

    

     

    
    

     

       respective layers of the network.  For example, if the list
     
    
   

    

     

    
    

     

       was [2, 3, 1] then it would be a three-layer network, with the
     
    
   

    

     

    
    

     

       first layer containing 2 neurons, the second layer 3 neurons,
     
    
   

    

     

    
    

     

       and the third layer 1 neuron.  The biases and weights for the
     
    
   

    

     

    
    

     

       network are initialized randomly, using a Gaussian
     
    
   

    

     

    
    

     

       distribution with mean 0, and variance 1.  Note that the first
     
    
   

    

     

    
    

     

       layer is assumed to be an input layer, and by convention we
     
    
   

    

     

    
    

     

       won't set any biases for those neurons, since biases are only
     
    
   

    

     

    
    

     

       ever used in computing the outputs from later layers."""
     
    
   

    

     

    
    

     

       self.num_layers = len(sizes) 
     
    
   

    

     

    
    

     

       self.sizes = sizes 
     
    
   

    

     

    
    

     

       self.biases = [np.random.randn(y, 1) for y in sizes[1:]]
     
    
   

    

     

    
    

     
  
     
    
   

    

     

    
    

     

       self.weights = [np.random.randn(y, x) for x, y in zip(sizes[:-1], sizes[1:])]
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def feedforward(self, a):   
     
    
   

    

     

    
    

     

       """Return the output of the network if ``a`` is input."""
     
    
   

    

     

    
    

     

       for b, w in zip(self.biases, self.weights):
     
    
   

    

     

    
    

     

       a = sigmoid(np.dot(w, a)+b)
     
    
   

    

     

    
    

     

       return a
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def SGD(self, training_data, epochs, mini_batch_size, eta, test_data=None):
     
    
   

    

     

    
    

     

       """Train the neural network using mini-batch stochastic
     
    
   

    

     

    
    

     

       gradient descent.  The ``training_data`` is a list of tuples
     
    
   

    

     

    
    

     

       ``(x, y)`` representing the training inputs and the desired
     
    
   

    

     

    
    

     

       outputs.  The other non-optional parameters are
     
    
   

    

     

    
    

     

       self-explanatory.  If ``test_data`` is provided then the
     
    
   

    

     

    
    

     

       network will be evaluated against the test data after each
     
    
   

    

     

    
    

     

       epoch, and partial progress printed out.  This is useful for
     
    
   

    

     

    
    

     

       tracking progress, but slows things down substantially."""
     
    
   

    

     

    
    

     

       if test_data: 
     
    
   

    

     

    
    

     

       n_test = len(test_data) 
     
    
   

    

     

    
    

     

       n = len(training_data) 
     
    
   

    

     

    
    

     

       for j in xrange(epochs): 
     
    
   

    

     

    
    

     

       random.shuffle(training_data) 
     
    
   

    

     

    
    

     

       mini_batches = [training_data[k:k+mini_batch_size]
     
    
   

    

     

    
    

     

       for k in xrange(0, n, mini_batch_size)]  
     
    
   

    

     

    
    

     

       for mini_batch in mini_batches: 
     
    
   

    

     

    
    

     

       self.update_mini_batch(mini_batch, eta)
     
    
   

    

     

    
    

     

       if test_data: 
     
    
   

    

     

    
    

     

       print ("Epoch {0}: {1} / {2}".format(j, self.evaluate(test_data), n_test))
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       else: 
     
    
   

    

     

    
    

     

       print ("Epoch {0} complete".format(j))
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def update_mini_batch(self, mini_batch, eta):   
     
    
   

    

     

    
    

     

       """Update the network's weights and biases by applying
     
    
   

    

     

    
    

     

       gradient descent using backpropagation to a single mini batch.
     
    
   

    

     

    
    

     

       The ``mini_batch`` is a list of tuples ``(x, y)``, and ``eta``
     
    
   

    

     

    
    

     

       is the learning rate."""
     
    
   

    

     

    
    

     

       nabla_b = [np.zeros(b.shape) for b in self.biases]   
     
    
   

    

     

    
    

     

       nabla_w = [np.zeros(w.shape) for w in self.weights]
     
    
   

    

     

    
    

     

       for x, y in mini_batch:   
     
    
   

    

     

    
    

     

       delta_nabla_b, delta_nabla_w = self.backprop(x, y)  
     
    
   

    

     

    
    

     

       nabla_b = [nb+dnb for nb, dnb in zip(nabla_b, delta_nabla_b)]  
     
    
   

    

     

    
    

     

       nabla_w = [nw+dnw for nw, dnw in zip(nabla_w, delta_nabla_w)]
     
    
   

    

     

    
    

     

       self.weights = [w-(eta/len(mini_batch))*nw for w, nw in zip(self.weights, nabla_w)]
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       self.biases = [b-(eta/len(mini_batch))*nb  for b, nb in zip(self.biases, nabla_b)]
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def backprop(self, x, y):  
     
    
   

    

     

    
    

     

       """Return a tuple ``(nabla_b, nabla_w)`` representing the
     
    
   

    

     

    
    

     

       gradient for the cost function C_x.  ``nabla_b`` and
     
    
   

    

     

    
    

     

       ``nabla_w`` are layer-by-layer lists of numpy arrays, similar
     
    
   

    

     

    
    

     

       to ``self.biases`` and ``self.weights``."""
     
    
   

    

     

    
    

     

       nabla_b = [np.zeros(b.shape) for b in self.biases]
     
    
   

    

     

    
    

     

       nabla_w = [np.zeros(w.shape) for w in self.weights]
     
    
   

    

     

    
    

     

       # feedforward
     
    
   

    

     

    
    

     

       activation = x
     
    
   

    

     

    
    

     

       activations = [x] # list to store all the activations, layer by layer
     
    
   

    

     

    
    

     

       zs = [] # list to store all the z vectors, layer by layer
     
    
   

    

     

    
    

     

       for b, w in zip(self.biases, self.weights):
     
    
   

    

     

    
    

     

       z = np.dot(w, activation)+b
     
    
   

    

     

    
    

     

       zs.append(z)
     
    
   

    

     

    
    

     

       activation = sigmoid(z)
     
    
   

    

     

    
    

     

       activations.append(activation)
     
    
   

    

     

    
    

     

       # backward pass
     
    
   

    

     

    
    

     

       delta = self.cost_derivative(activations[-1], y) * \
     
    
   

    

     

    
    

     

       sigmoid_prime(zs[-1])
     
    
   

    

     

    
    

     

       nabla_b[-1] = delta
     
    
   

    

     

    
    

     

       nabla_w[-1] = np.dot(delta, activations[-2].transpose())
     
    
   

    

     

    
    

     

       # Note that the variable l in the loop below is used a little
     
    
   

    

     

    
    

     

       # differently to the notation in Chapter 2 of the book.  Here,
     
    
   

    

     

    
    

     

       # l = 1 means the last layer of neurons, l = 2 is the
     
    
   

    

     

    
    

     

       # second-last layer, and so on.  It's a renumbering of the
     
    
   

    

     

    
    

     

       # scheme in the book, used here to take advantage of the fact
     
    
   

    

     

    
    

     

       # that Python can use negative indices in lists.
     
    
   

    

     

    
    

     

       for l in xrange(2, self.num_layers):
     
    
   

    

     

    
    

     

       z = zs[-l]
     
    
   

    

     

    
    

     

       sp = sigmoid_prime(z)
     
    
   

    

     

    
    

     

       delta = np.dot(self.weights[-l+1].transpose(), delta) * sp
     
    
   

    

     

    
    

     

       nabla_b[-l] = delta
     
    
   

    

     

    
    

     

       nabla_w[-l] = np.dot(delta, activations[-l-1].transpose())
     
    
   

    

     

    
    

     

       return (nabla_b, nabla_w)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def evaluate(self, test_data):#评估，
     
    
   

    

     

    
    

     

       """Return the number of test inputs for which the neural
     
    
   

    

     

    
    

     

       network outputs the correct result. Note that the neural
     
    
   

    

     

    
    

     

       network's output is assumed to be the index of whichever
     
    
   

    

     

    
    

     

       neuron in the final layer has the highest activation."""
     
    
   

    

     

    
    

     

       test_results = [(np.argmax(self.feedforward(x)), y)
     
    
   

    

     

    
    

     

       for (x, y) in test_data]
     
    
   

    

     

    
    

     

       return sum(int(x == y) for (x, y) in test_results) 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       def cost_derivative(self, output_activations, y):  
     
    
   

    

     

    
    

     

       """Return the vector of partial derivatives \partial C_x /
     
    
   

    

     

    
    

     

       \partial a for the output activations."""
     
    
   

    

     

    
    

     

       return (output_activations-y)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      def sigmoid(z):   
     
    
   

    

     

    
    

     

       """The sigmoid function."""
     
    
   

    

     

    
    

     

       return 1.0/(1.0+np.exp(-z))
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      def sigmoid_prime(z):
     
    
   

    

     

    
    

     

       """Derivative of the sigmoid function."""
     
    
   

    

     

    
    

     

       return sigmoid(z)*(1-sigmoid(z))
     
    
  
 

  

   

    

     

    
    

     

      import pickle as cPickle
     
    
   

    

     

    
    

     

      import gzip
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      import numpy as np
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      def load_data():
     
    
   

    

     

    
    

     

       """Return the MNIST data as a tuple containing the training data,
     
    
   

    

     

    
    

     

       the validation data, and the test data.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       The ``training_data`` is returned as a tuple with two entries.
     
    
   

    

     

    
    

     

       The first entry contains the actual training images.  This is a
     
    
   

    

     

    
    

     

       numpy ndarray with 50,000 entries.  Each entry is, in turn, a
     
    
   

    

     

    
    

     

       numpy ndarray with 784 values, representing the 28 * 28 = 784
     
    
   

    

     

    
    

     

       pixels in a single MNIST image.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       The second entry in the ``training_data`` tuple is a numpy ndarray
     
    
   

    

     

    
    

     

       containing 50,000 entries.  Those entries are just the digit
     
    
   

    

     

    
    

     

       values (0...9) for the corresponding images contained in the first
     
    
   

    

     

    
    

     

       entry of the tuple.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       The ``validation_data`` and ``test_data`` are similar, except
     
    
   

    

     

    
    

     

       each contains only 10,000 images.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       This is a nice data format, but for use in neural networks it's
     
    
   

    

     

    
    

     

       helpful to modify the format of the ``training_data`` a little.
     
    
   

    

     

    
    

     

       That's done in the wrapper function ``load_data_wrapper()``, see
     
    
   

    

     

    
    

     

       below.
     
    
   

    

     

    
    

     

       """
     
    
   

    

     

    
    

     

       f = gzip.open('../data/mnist.pkl.gz', 'rb')
     
    
   

    

     

    
    

     

       training_data, validation_data, test_data = cPickle.load(f,encoding='bytes')  #(f,encoding='bytes')
     
    
   

    

     

    
    

     

       f.close()
     
    
   

    

     

    
    

     

       return (training_data, validation_data, test_data)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      def load_data_wrapper():
     
    
   

    

     

    
    

     

       """Return a tuple containing ``(training_data, validation_data,
     
    
   

    

     

    
    

     

       test_data)``. Based on ``load_data``, but the format is more
     
    
   

    

     

    
    

     

       convenient for use in our implementation of neural networks.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       In particular, ``training_data`` is a list containing 50,000
     
    
   

    

     

    
    

     

       2-tuples ``(x, y)``.  ``x`` is a 784-dimensional numpy.ndarray
     
    
   

    

     

    
    

     

       containing the input image.  ``y`` is a 10-dimensional
     
    
   

    

     

    
    

     

       numpy.ndarray representing the unit vector corresponding to the
     
    
   

    

     

    
    

     

       correct digit for ``x``.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       ``validation_data`` and ``test_data`` are lists containing 10,000
     
    
   

    

     

    
    

     

       2-tuples ``(x, y)``.  In each case, ``x`` is a 784-dimensional
     
    
   

    

     

    
    

     

       numpy.ndarry containing the input image, and ``y`` is the
     
    
   

    

     

    
    

     

       corresponding classification, i.e., the digit values (integers)
     
    
   

    

     

    
    

     

       corresponding to ``x``.
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

       Obviously, this means we're using slightly different formats for
     
    
   

    

     

    
    

     

       the training data and the validation / test data.  These formats
     
    
   

    

     

    
    

     

       turn out to be the most convenient for use in our neural network
     
    
   

    

     

    
    

     

       code."""
     
    
   

    

     

    
    

     

       tr_d, va_d, te_d = load_data()
     
    
   

    

     

    
    

     

       training_inputs = [np.reshape(x, (784, 1)) for x in tr_d[0]]
     
    
   

    

     

    
    

     

       training_results = [vectorized_result(y) for y in tr_d[1]]
     
    
   

    

     

    
    

     

       training_data = zip(training_inputs, training_results)
     
    
   

    

     

    
    

     

       validation_inputs = [np.reshape(x, (784, 1)) for x in va_d[0]]
     
    
   

    

     

    
    

     

       validation_data = zip(validation_inputs, va_d[1])
     
    
   

    

     

    
    

     

       test_inputs = [np.reshape(x, (784, 1)) for x in te_d[0]]
     
    
   

    

     

    
    

     

       test_data = zip(test_inputs, te_d[1])
     
    
   

    

     

    
    

     

       return (training_data, validation_data, test_data)
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      def vectorized_result(j):
     
    
   

    

     

    
    

     

       """Return a 10-dimensional unit vector with a 1.0 in the jth
     
    
   

    

     

    
    

     

       position and zeroes elsewhere.  This is used to convert a digit
     
    
   

    

     

    
    

     

       (0...9) into a corresponding desired output from the neural
     
    
   

    

     

    
    

     

       network."""
     
    
   

    

     

    
    

     

       e = np.zeros((10, 1))
     
    
   

    

     

    
    

     

       e[j] = 1.0
     
    
   

    

     

    
    

     

       return e
     
    
  
 

DL之NN：利用(本地数据集50000张数据集)调用自定义神经网络network.py实现手写图片识别94%

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