这篇文章在前一篇文章：python构建深度神经网络（DNN）的基础上，添加了一下几个内容：

1) 正则化项

2） 调出中间损失函数的输出

3） 构建了交叉损失函数

4） 将训练好的网络进行保存，并调用用来测试新数据

1 数据预处理

#!/usr/bin/env python # -*- coding: utf-8 -*- # @Time : 2017-03-12 15:11 # @Author : CC # @File : net_load_data.py from numpy import * import numpy as np import cPickle def load_data(): """载入解压后的数据，并读取""" with open('data/mnist_pkl/mnist.pkl','rb') as f: try: train_data,validation_data,test_data = cPickle.load(f) print " the file open sucessfully" # print train_data[0].shape #(50000,784) # print train_data[1].shape #(50000,) return (train_data,validation_data,test_data) except EOFError: print 'the file open error' return None def data_transform(): """将数据转化为计算格式""" t_d,va_d,te_d = load_data() # print t_d[0].shape # (50000,784) # print te_d[0].shape # (10000,784) # print va_d[0].shape # (10000,784) # n1 = [np.reshape(x,784,1) for x in t_d[0]] # 将5万个数据分别逐个取出化成（784,1），逐个排列 n = [np.reshape(x, (784, 1)) for x in t_d[0]] # 将5万个数据分别逐个取出化成（784,1），逐个排列 # print 'n1',n1[0].shape # print 'n',n[0].shape m = [vectors(y) for y in t_d[1]] # 将5万标签（50000,1）化为（10,50000） train_data = zip(n,m) # 将数据与标签打包成元组形式 n = [np.reshape(x, (784, 1)) for x in va_d[0]] # 将5万个数据分别逐个取出化成（784,1），排列 validation_data = zip(n,va_d[1]) # 没有将标签数据矢量化 n = [np.reshape(x, (784, 1)) for x in te_d[0]] # 将5万个数据分别逐个取出化成（784,1），排列 test_data = zip(n, te_d[1]) # 没有将标签数据矢量化 # print train_data[0][0].shape #(784,） # print "len(train_data[0])",len(train_data[0]) #2 # print "len(train_data[100])",len(train_data[100]) #2 # print "len(train_data[0][0])", len(train_data[0][0]) #784 # print "train_data[0][0].shape", train_data[0][0].shape #（784,1） # print "len(train_data)", len(train_data) #50000 # print train_data[0][1].shape #(10,1) # print test_data[0][1] # 7 return (train_data,validation_data,test_data) def vectors(y): "赋予标签" label = np.zeros((10,1)) label[y] = 1.0 #浮点计算 return label

2 网络定义和训练

#!/usr/bin/env python # -*- coding: utf-8 -*- # @Time : 2017-03-28 10:18 # @Author : CC # @File : net_network2.py from numpy import * import numpy as np import operator import json # import sys class QuadraticCost(): """定义二次代价函数类的方法""" @staticmethod def fn(a,y): cost = 0.5*np.linalg.norm(a-y)**2 return cost @staticmethod def delta(z,a,y): delta = (a-y)*sig_derivate(z) return delta class CrossEntroyCost(): """定义交叉熵函数类的方法""" @staticmethod def fn(a, y): cost = np.sum(np.nan_to_num(-y*np.log(a)-(1-y)*np.log(1-a))) # not a number---0, inf---larger number return cost @staticmethod def delta(z, a, y): delta = (a - y) return delta class Network(object): """定义网络结构和方法""" def __init__(self,sizes,cost): self.num_layer = len(sizes) self.sizes = sizes self.cost = cost # print "self.cost.__name__:",self.cost.__name__ # CrossEntropyCost self.default_weight_initializer() def default_weight_initializer(self): """权值初始化""" self.bias = [np.random.rand(x, 1) for x in self.sizes[1:]] self.weight = [np.random.randn(y, x)/float(np.sqrt(x)) for (x, y) in zip(self.sizes[:-1], self.sizes[1:])] def large_weight_initializer(self): """权值另一种初始化""" self.bias = [np.random.rand(x, 1) for x in self.sizes[1:]] self.weight = [np.random.randn(y, x) for x, y in zip(self.sizes[:-1], self.sizes[1:])] def forward(self,a): """forward the network""" for w,b in zip(self.weight,self.bias): a=sigmoid(np.dot(w,a)+b) return a def SGD(self,train_data,min_batch_size,epochs,eta,test_data=False, lambd = 0, monitor_train_cost = False, monitor_train_accuracy = False, monitor_test_cost=False, monitor_test_accuracy=False ): """1)Set the train_data,shuffle; 2) loop the epoches, 3) set the min_batches,and rule of update""" if test_data: n_test=len(test_data) n = len(train_data) for i in xrange(epochs): random.shuffle(train_data) min_batches = [train_data[k:k+min_batch_size] for k in xrange(0,n,min_batch_size)] for min_batch in min_batches: # 每次提取一个批次的样本 self.update_minbatch_parameter(min_batch,eta,lambd,n) train_cost = [] if monitor_train_cost: cost1 = self.total_cost(train_data,lambd,cont=False) train_cost.append(cost1) print "epoche {0},train_cost: {1}".format(i,cost1) if monitor_train_accuracy: accuracy = self.accuracy(train_data,cont=True) train_cost.append(accuracy) print "epoche {0}/{1},train_accuracy: {2}".format(i,epochs,accuracy) test_cost = [] if monitor_test_cost: cost1 = self.total_cost(test_data,lambd) test_cost.append(cost1) print "epoche {0},test_cost: {1}".format(i,cost1) test_accuracy = [] if monitor_test_accuracy: accuracy = self.accuracy(test_data) test_cost.append(accuracy) print "epoche:{0}/{1},test_accuracy:{2}".format(i,epochs,accuracy) self.save(filename= "net_save") #保存网络网络参数 def total_cost(self,train_data,lambd,cont=True): cost1 = 0.0 for x,y in train_data: a = self.forward(x) if cont: y = vectors(y) #将测试样本标签化为矩阵 cost1 += (self.cost).fn(a,y)/len(train_data) cost1 += lambd/len(train_data)*np.sum(np.linalg.norm(weight)**2 for weight in self.weight) #加上权值项 return cost1 def accuracy(self,train_data,cont=False): if cont: output1 = [(np.argmax(self.forward(x)),np.argmax(y)) for (x,y) in train_data] else: output1 = [(np.argmax(self.forward(x)), y) for (x, y) in train_data] return sum(int(out1 == y) for (out1, y) in output1) def update_minbatch_parameter(self,min_batch, eta,lambd,n): """1) determine the weight and bias 2) calculate the the delta 3) update the data """ able_b = [np.zeros(b.shape) for b in self.bias] able_w=[np.zeros(w.shape) for w in self.weight] for x,y in min_batch: #每次只取一个样本？ deltab,deltaw = self.backprop(x,y) able_b =[a_b+dab for a_b, dab in zip(able_b,deltab)] #实际上对dw,db做批次累加，最后小批次取平均 able_w = [a_w + daw for a_w, daw in zip(able_w, deltaw)] self.weight = [weight - eta * (dw) / len(min_batch)- eta*(lambd*weight)/n for weight, dw in zip(self.weight,able_w) ] #增加正则化项：eta*lambda/m *weight self.bias = [bias - eta * db / len(min_batch) for bias, db in zip(self.bias, able_b)] def backprop(self,x,y): """" 1) clacu the forward value 2) calcu the delta： delta =(y-f(z)); deltak = delta*w(k)*fz(k-1)' 3) clacu the delta in every layer: deltab=delta; deltaw=delta*fz(k-1)""" deltab = [np.zeros(b.shape) for b in self.bias] deltaw = [np.zeros(w.shape) for w in self.weight] zs = [] activate = x activates = [x] for w,b in zip(self.weight,self.bias): z =np.dot(w, activate) +b zs.append(z) activate = sigmoid(z) activates.append(activate) # backprop delta = self.cost.delta(zs[-1],activates[-1],y) #调用不同代价函数的方法求梯度 deltab[-1] = delta deltaw[-1] = np.dot(delta ,activates[-2].transpose()) for i in xrange(2,self.num_layer): z = zs[-i] delta = np.dot(self.weight[-i+1].transpose(),delta)* sig_derivate(z) deltab[-i] = delta deltaw[-i] = np.dot(delta,activates[-i-1].transpose()) return (deltab,deltaw) def save(self,filename): """将训练好的网络采用json(java script object notation)将对象保存成字符串保存，用于生产部署 encoder=json.dumps(data) python 原始类型(没有数组类型)向 json 类型的转化对照表： python json dict object list/tuple arrary int/long/float number .tolist() 将数组转化为列表 >>> a = np.array([[1, 2], [3, 4]]) >>> list(a) [array([1, 2]), array([3, 4])] >>> a.tolist() [[1, 2], [3, 4]] """ data = {"sizes": self.sizes,"weight": [weight.tolist() for weight in self.weight], "bias": ([bias.tolist() for bias in self.bias]), "cost": str(self.cost.__name__)} # 保存网络训练好的权值，偏置，交叉熵参数。 f = open(filename, "w") json.dump(data,f) f.close() def load_net(filename): """采用data=json.load(json.dumps(data))进行解码， decoder = json.load(encoder) 编码后和解码后键不会按照原始data的键顺序排列，但每个键对应的值不会变 载入训练好的网络用于测试""" f = open(filename,"r") data = json.load(f) f.close() # print "data[cost]", getattr(sys.modules[__name__], data["cost"])#获得属性__main__.CrossEntropyCost # print "data[cost]", data["cost"], data["sizes"] net = Network(data["sizes"], cost=data["cost"]) #网络初始化 net.weight = [np.array(w) for w in data["weight"]] #赋予训练好的权值,并将list--->array net.bias = [np.array(b) for b in data["bias"]] return net def sig_derivate(z): """derivate sigmoid""" return sigmoid(z) * (1-sigmoid(z)) def sigmoid(x): sigm=1.0/(1.0+exp(-x)) return sigm def vectors(y): """赋予标签""" label = np.zeros((10,1)) label[y] = 1.0 #浮点计算 return label

3） 网络测试

#!/usr/bin/env python # -*- coding: utf-8 -*- # @Time : 2017-03-12 15:24 # @Author : CC # @File : net_test.py import net_load_data # net_load_data.load_data() train_data,validation_data,test_data = net_load_data.data_transform() import net_network2 as net cost = net.QuadraticCost cost = net.CrossEntroyCost lambd = 0 net1 = net.Network([784,50,10],cost) min_batch_size = 30 eta = 3.0 epoches = 2 net1.SGD(train_data,min_batch_size,epoches,eta,test_data, lambd, monitor_train_cost=True, monitor_train_accuracy=True, monitor_test_cost=True, monitor_test_accuracy=True ) print "complete"

4 调用训练好的网络进行测试

#!/usr/bin/env python # -*- coding: utf-8 -*- # @Time : 2017-03-28 17:27 # @Author : CC # @File : forward_test.py import numpy as np # 对训练好的网络直接进行调用，并用测试样本进行测试 import net_load_data #导入测试数据 import net_network2 as net train_data,validation_data,test_data = net_load_data.data_transform() net = net.load_net(filename= "net_save") #导入网络 output = [(np.argmax(net.forward(x)),y) for (x,y) in test_data] #测试 print sum(int(y1 == y2) for (y1,y2) in output) #输出最终值

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