一个简单的卷积神经网络——SimpleConvNet.py

# coding: utf-8 import sys, os sys.path.append(os.pardir) import pickle from collections import OrderedDict from layers import * from gradient import numerical_gradient # pickle 是一个 python 中, 压缩/保存/提取 文件的模块。最一般的使用方式非常简单。 class SimpleConvNet: """ 简单的卷积神经网络 conv - relu - pool - affine - relu - affine - softmax Parmameters: input_size: 输入数据大小（MNIST的情况下为784） hidden_size: 隐藏层的神经元数量列表（e.g. [100, 100, 100]） output_size: 输出大小(MNIST下为10) activation: ‘relu’和‘sigmoid’ ！ weight_init_std: 指定权重的标准差（0.01）！ 指定'relu'或'he'的情况下设定“He的初始值” 指定'sigmoid'或'xavier'的情况下设定“Xavier的初始值” """ def __init__(self, input_dim=(1, 28, 28), conv_param={'fliter_num': 30, 'filter_size':5, 'pad':0, 'stride':1}, hidden_size=100, output_size=10, weight_init_std=0.01): filter_num = conv_param['filter_num'] filter_size = conv_param['filter_size'] filter_pad = conv_param['pad'] filter_stride = conv_param['stride'] input_size = input_dim[1] conv_output_size = (input_size - filter_size + 2 * filter_pad) / filter_stride + 1 pool_output_size = int(filter_num * (conv_output_size / 2) * (conv_output_size / 2)) # 初始化权重 self.params = {} self.params['W1'] = weight_init_std * np.random.randn(filter_num, input_dim[0], filter_size, filter_size) self.params['b1'] = np.zeros(filter_num) self.params['W2'] = weight_init_std * np.random.randn(pool_output_size, hidden_size) self.params['b2'] = np.zeros(hidden_size) self.params['W3'] = weight_init_std * np.random.randn(hidden_size, output_size) self.params['b3'] = np.zeros(output_size) # 生成层 self.layers = OrderedDict() self.layers['Conv1'] = Convolution(self.params['W1'], self.params['b1'], conv_param['stride'], conv_param['pad']) self.layers['Relu1'] = Relu() self.layers['Pool1'] = Pooling(pool_h=2, pool_w=2, stride=2) self.layers['Affine1'] = Affine(self.params['W2'], self.params['b2']) self.layers['Relu2'] = Relu() self.layers['Affine2'] = Affine(self.params['W3'], self.params['b3']) self.last_layer = SoftmaxWithLoss() # ---------------------------------------------预测函数------------------------------------------------- def predict(self, x): for layer in self.layers.values(): x = layer.forward(x) return x # ----------------------------------------------损失函数--------------------------------------------------- def loss(self, x, t): """求损失函数 参数x是输入数据、t是教师标签 """ y = self.predict(x) return self.last_layer.forward(y, t) # ----------------------------------------------精度算法-------------------------------------------------- def accuracy(self, x, t, batch_size=100): if t.ndim != 1: t = np.argmax(t, axis=1) acc = 0.0 for i in range(int(x.shape[0] / batch_size)): tx = x[i * batch_size:(i + 1) * batch_size] tt = t[i * batch_size:(i + 1) * batch_size] y = self.predict(tx) y = np.argmax(y, axis=1) acc += np.sum(y == tt) return acc / x.shape[0] # -----------------------------------------求梯度，数值微分-------------------------------------------------------- def numerical_gradient(self, x, t): """求梯度（数值微分） Parameters ---------- x : 输入数据 t : 教师标签 Returns ------- 具有各层的梯度的字典变量 grads['W1']、grads['W2']、...是各层的权重 grads['b1']、grads['b2']、...是各层的偏置 """ loss_w = lambda w: self.loss(x, t) grads = {} for idx in (1, 2, 3): grads['W' + str(idx)] = numerical_gradient(loss_w, self.params['W' + str(idx)]) grads['b' + str(idx)] = numerical_gradient(loss_w, self.params['b' + str(idx)]) return grads # -------------------------------------反向传播时求解梯度--------------------------------------------------------- def gradient(self, x, t): """求梯度（误差反向传播法） Parameters ---------- x : 输入数据 t : 教师标签 Returns ------- 具有各层的梯度的字典变量 grads['W1']、grads['W2']、...是各层的权重 grads['b1']、grads['b2']、...是各层的偏置 """ # forward self.loss(x, t) # backward dout = 1 dout = self.last_layer.backward(dout) layers = list(self.layers.values()) layers.reverse() for layer in layers: dout = layer.backward(dout) # 设定 grads = {} grads['W1'], grads['b1'] = self.layers['Conv1'].dW, self.layers['Conv1'].db grads['W2'], grads['b2'] = self.layers['Affine1'].dW, self.layers['Affine1'].db grads['W3'], grads['b3'] = self.layers['Affine2'].dW, self.layers['Affine2'].db return grads # ---------------------------------------保存参数，利用pickle----------------------------------------------------- def save_params(self, file_name="params.pkl"): params = {} for key, val in self.params.items(): params[key] = val with open(file_name, 'wb') as f: pickle.dump(params, f) # ------------------------------------加载参数，利用pickle---------------------------------------------------- def load_params(self, file_name="params.pkl"): with open(file_name, 'rb') as f: params = pickle.load(f) for key, val in params.items(): self.params[key] = val for i, key in enumerate(['Conv1', 'Affine1', 'Affine2']): self.layers[key].W = self.params['W' + str(i+1)] self.layers[key].b = self.params['b' + str(i+1)]