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不懂keras實現多種分類網絡的方法?其實想解決這個問題也不難,下面讓小編帶著大家一起學習怎么去解決,希望大家閱讀完這篇文章后大所收獲。
Keras應該是最簡單的一種深度學習框架了,入門非常的簡單.
簡單記錄一下keras實現多種分類網絡:如AlexNet、Vgg、ResNet
采用kaggle貓狗大戰的數據作為數據集.
由于AlexNet采用的是LRN標準化,Keras沒有內置函數實現,這里用batchNormalization代替
收件建立一個model.py的文件,里面存放著alexnet,vgg兩種模型,直接導入就可以了
#coding=utf-8 from keras.models import Sequential from keras.layers import Dense, Dropout, Activation, Flatten from keras.layers import Conv2D, MaxPooling2D, ZeroPadding2D, BatchNormalization from keras.layers import * from keras.layers.advanced_activations import LeakyReLU,PReLU from keras.models import Model def keras_batchnormalization_relu(layer): BN = BatchNormalization()(layer) ac = PReLU()(BN) return ac def AlexNet(resize=227, classes=2): model = Sequential() # 第一段 model.add(Conv2D(filters=96, kernel_size=(11, 11), strides=(4, 4), padding='valid', input_shape=(resize, resize, 3), activation='relu')) model.add(BatchNormalization()) model.add(MaxPooling2D(pool_size=(3, 3), strides=(2, 2), padding='valid')) # 第二段 model.add(Conv2D(filters=256, kernel_size=(5, 5), strides=(1, 1), padding='same', activation='relu')) model.add(BatchNormalization()) model.add(MaxPooling2D(pool_size=(3, 3), strides=(2, 2), padding='valid')) # 第三段 model.add(Conv2D(filters=384, kernel_size=(3, 3), strides=(1, 1), padding='same', activation='relu')) model.add(Conv2D(filters=384, kernel_size=(3, 3), strides=(1, 1), padding='same', activation='relu')) model.add(Conv2D(filters=256, kernel_size=(3, 3), strides=(1, 1), padding='same', activation='relu')) model.add(MaxPooling2D(pool_size=(3, 3), strides=(2, 2), padding='valid')) # 第四段 model.add(Flatten()) model.add(Dense(4096, activation='relu')) model.add(Dropout(0.5)) model.add(Dense(4096, activation='relu')) model.add(Dropout(0.5)) model.add(Dense(1000, activation='relu')) model.add(Dropout(0.5)) # Output Layer model.add(Dense(classes,activation='softmax')) # model.add(Activation('softmax')) return model def AlexNet2(inputs, classes=2, prob=0.5): ''' 自己寫的函數,嘗試keras另外一種寫法 :param inputs: 輸入 :param classes: 類別的個數 :param prob: dropout的概率 :return: 模型 ''' # Conv2D(32, (3, 3), dilation_rate=(2, 2), padding='same')(inputs) print "input shape:", inputs.shape conv1 = Conv2D(filters=96, kernel_size=(11, 11), strides=(4, 4), padding='valid')(inputs) conv1 = keras_batchnormalization_relu(conv1) print "conv1 shape:", conv1.shape pool1 = MaxPool2D(pool_size=(3, 3), strides=(2, 2))(conv1) print "pool1 shape:", pool1.shape conv2 = Conv2D(filters=256, kernel_size=(5, 5), padding='same')(pool1) conv2 = keras_batchnormalization_relu(conv2) print "conv2 shape:", conv2.shape pool2 = MaxPool2D(pool_size=(3, 3), strides=(2, 2))(conv2) print "pool2 shape:", pool2.shape conv3 = Conv2D(filters=384, kernel_size=(3, 3), padding='same')(pool2) conv3 = PReLU()(conv3) print "conv3 shape:", conv3.shape conv4 = Conv2D(filters=384, kernel_size=(3, 3), padding='same')(conv3) conv4 = PReLU()(conv4) print "conv4 shape:", conv4 conv5 = Conv2D(filters=256, kernel_size=(3, 3), padding='same')(conv4) conv5 = PReLU()(conv5) print "conv5 shape:", conv5 pool3 = MaxPool2D(pool_size=(3, 3), strides=(2, 2))(conv5) print "pool3 shape:", pool3.shape dense1 = Flatten()(pool3) dense1 = Dense(4096, activation='relu')(dense1) print "dense2 shape:", dense1 dense1 = Dropout(prob)(dense1) # print "dense1 shape:", dense1 dense2 = Dense(4096, activation='relu')(dense1) print "dense2 shape:", dense2 dense2 = Dropout(prob)(dense2) # print "dense2 shape:", dense2 predict= Dense(classes, activation='softmax')(dense2) model = Model(inputs=inputs, outputs=predict) return model def vgg13(resize=224, classes=2, prob=0.5): model = Sequential() model.add(Conv2D(64, (3, 3), strides=(1, 1), input_shape=(resize, resize, 3), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(64, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(128, (3, 2), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(128, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(256, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(256, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Flatten()) model.add(Dense(4096, activation='relu')) model.add(Dropout(prob)) model.add(Dense(4096, activation='relu')) model.add(Dropout(prob)) model.add(Dense(classes, activation='softmax')) return model def vgg16(resize=224, classes=2, prob=0.5): model = Sequential() model.add(Conv2D(64, (3, 3), strides=(1, 1), input_shape=(resize, resize, 3), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(64, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(128, (3, 2), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(128, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(256, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(256, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(256, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(Conv2D(512, (3, 3), strides=(1, 1), padding='same', activation='relu', kernel_initializer='uniform')) model.add(MaxPooling2D(pool_size=(2, 2))) model.add(Flatten()) model.add(Dense(4096, activation='relu')) model.add(Dropout(prob)) model.add(Dense(4096, activation='relu')) model.add(Dropout(prob)) model.add(Dense(classes, activation='softmax')) return model
然后建立一個train.py文件,用于讀取數據和訓練數據的.
#coding=utf-8 import keras import cv2 import os import numpy as np import model import modelResNet import tensorflow as tf from keras.layers import Input, Dense from keras.preprocessing.image import ImageDataGenerator resize = 224 batch_size = 128 path = "/home/hjxu/PycharmProjects/01_cats_vs_dogs/data" trainDirectory = '/home/hjxu/PycharmProjects/01_cats_vs_dogs/data/train/' def load_data(): imgs = os.listdir(path + "/train/") num = len(imgs) train_data = np.empty((5000, resize, resize, 3), dtype="int32") train_label = np.empty((5000, ), dtype="int32") test_data = np.empty((5000, resize, resize, 3), dtype="int32") test_label = np.empty((5000, ), dtype="int32") for i in range(5000): if i % 2: train_data[i] = cv2.resize(cv2.imread(path + '/train/' + 'dog.' + str(i) + '.jpg'), (resize, resize)) train_label[i] = 1 else: train_data[i] = cv2.resize(cv2.imread(path + '/train/' + 'cat.' + str(i) + '.jpg'), (resize, resize)) train_label[i] = 0 for i in range(5000, 10000): if i % 2: test_data[i-5000] = cv2.resize(cv2.imread(path + '/train/' + 'dog.' + str(i) + '.jpg'), (resize, resize)) test_label[i-5000] = 1 else: test_data[i-5000] = cv2.resize(cv2.imread(path + '/train/' + 'cat.' + str(i) + '.jpg'), (resize, resize)) test_label[i-5000] = 0 return train_data, train_label, test_data, test_label def main(): train_data, train_label, test_data, test_label = load_data() train_data, test_data = train_data.astype('float32'), test_data.astype('float32') train_data, test_data = train_data/255, test_data/255 train_label = keras.utils.to_categorical(train_label, 2) ''' #one_hot轉碼,如果使用 categorical_crossentropy,就需要用到to_categorical函數完成轉碼 ''' test_label = keras.utils.to_categorical(test_label, 2) inputs = Input(shape=(224, 224, 3)) modelAlex = model.AlexNet2(inputs, classes=2) ''' 導入模型 ''' modelAlex.compile(loss='categorical_crossentropy', optimizer='sgd', metrics=['accuracy']) ''' def compile(self, optimizer, loss, metrics=None, loss_weights=None, sample_weight_mode=None, **kwargs): optimizer:優化器,為預定義優化器名或優化器對象,參考優化器 loss: 損失函數,為預定義損失函數名或者一個目標函數 metrics:列表,包含評估模型在訓練和測試時的性能指標,典型用法是 metrics=['accuracy'] sample_weight_mode:如果需要按時間步為樣本賦值,需要將改制設置為"temoral" 如果想用自定義的性能評估函數:如下 def mean_pred(y_true, y_pred): return k.mean(y_pred) model.compile(loss = 'binary_crossentropy', metrics=['accuracy', mean_pred],...) 損失函數同理,再看 keras內置支持的損失函數有 mean_squared_error mean_absolute_error mean_absolute_percentage_error mean_squared_logarithmic_error squared_hinge hinge categorical_hinge logcosh categorical_crossentropy sparse_categorical_crossentropy binary_crossentropy kullback_leibler_divergence poisson cosine_proximity ''' modelAlex.summary() ''' # 打印模型信息 ''' modelAlex.fit(train_data, train_label, batch_size=batch_size, epochs=50, validation_split=0.2, shuffle=True) ''' def fit(self, x=None, # x:輸入數據 y=None, # y:標簽 Numpy array batch_size=32, # batch_size:訓練時,一個batch的樣本會被計算一次梯度下降 epochs=1, # epochs: 訓練的輪數,每個epoch會把訓練集循環一遍 verbose=1, # 日志顯示:0表示不在標準輸入輸出流輸出,1表示輸出進度條,2表示每個epoch輸出 callbacks=None, # 回調函數 validation_split=0., # 0-1的浮點數,用來指定訓練集一定比例作為驗證集,驗證集不參與訓練 validation_data=None, # (x,y)的tuple,是指定的驗證集 shuffle=True, # 如果是"batch",則是用來處理HDF5數據的特殊情況,將在batch內部將數據打亂 class_weight=None, # 字典,將不同的類別映射為不同的權值,用來在訓練過程中調整損失函數的 sample_weight=None, # 權值的numpy array,用于訓練的時候調整損失函數 initial_epoch=0, # 該參數用于從指定的epoch開始訓練,繼續之前的訓練 **kwargs): 返回:返回一個History的對象,其中History.history損失函數和其他指標的數值隨epoch變化的情況 ''' scores = modelAlex.evaluate(train_data, train_label, verbose=1) print(scores) scores = modelAlex.evaluate(test_data, test_label, verbose=1) print(scores) modelAlex.save('my_model_weights2.h6') def main2(): train_datagen = ImageDataGenerator(rescale=1. / 255, shear_range=0.2, zoom_range=0.2, horizontal_flip=True) test_datagen = ImageDataGenerator(rescale=1. / 255) train_generator = train_datagen.flow_from_directory(trainDirectory, target_size=(224, 224), batch_size=32, class_mode='binary') validation_generator = test_datagen.flow_from_directory(trainDirectory, target_size=(224, 224), batch_size=32, class_mode='binary') inputs = Input(shape=(224, 224, 3)) # modelAlex = model.AlexNet2(inputs, classes=2) modelAlex = model.vgg13(resize=224, classes=2, prob=0.5) # modelAlex = modelResNet.ResNet50(shape=224, classes=2) modelAlex.compile(loss='sparse_categorical_crossentropy', optimizer='sgd', metrics=['accuracy']) modelAlex.summary() modelAlex.fit_generator(train_generator, steps_per_epoch=1000, epochs=60, validation_data=validation_generator, validation_steps=200) modelAlex.save('model32.hdf5') # if __name__ == "__main__": ''' 如果數據是按照貓狗大戰的數據,都在同一個文件夾下,使用main()函數 如果數據按照貓和狗分成兩類,則使用main2()函數 ''' main2()
得到模型后該怎么測試一張圖像呢?
建立一個testOneImg.py腳本,代碼如下
#coding=utf-8 from keras.preprocessing.image import load_img#load_image作用是載入圖片 from keras.preprocessing.image import img_to_array from keras.applications.vgg16 import preprocess_input from keras.applications.vgg16 import decode_predictions import numpy as np import cv2 import model from keras.models import Sequential pats = '/home/hjxu/tf_study/catVsDogsWithKeras/my_model_weights.h6' modelAlex = model.AlexNet(resize=224, classes=2) # AlexModel = model.AlexNet(weightPath='/home/hjxu/tf_study/catVsDogsWithKeras/my_model_weights.h6') modelAlex.load_weights(pats) # img = cv2.imread('/home/hjxu/tf_study/catVsDogsWithKeras/111.jpg') img = cv2.resize(img, (224, 224)) x = img_to_array(img/255) # 三維(224,224,3) x = np.expand_dims(x, axis=0) # 四維(1,224,224,3)#因為keras要求的維度是這樣的,所以要增加一個維度 # x = preprocess_input(x) # 預處理 print(x.shape) y_pred = modelAlex.predict(x) # 預測概率 t1 = time.time() print("測試圖:", decode_predictions(y_pred)) # 輸出五個最高概率(類名, 語義概念, 預測概率) print y_pred
不得不說,Keras真心簡單方便。
補充知識:keras中的函數式API——殘差連接+權重共享的理解
1、殘差連接
# coding: utf-8 """殘差連接 residual connection: 是一種常見的類圖網絡結構,解決了所有大規模深度學習的兩個共性問題: 1、梯度消失 2、表示瓶頸 (甚至,向任何>10層的神經網絡添加殘差連接,都可能會有幫助) 殘差連接:讓前面某層的輸出作為后面某層的輸入,從而在序列網絡中有效地創造一條捷徑。 """ from keras import layers x = ... y = layers.Conv2D(128, 3, activation='relu', padding='same')(x) y = layers.Conv2D(128, 3, activation='relu', padding='same')(y) y = layers.Conv2D(128, 3, activation='relu', padding='same')(y) y = layers.add([y, x]) # 將原始x與輸出特征相加 # ---------------------如果特征圖尺寸不同,采用線性殘差連接------------------- x = ... y = layers.Conv2D(128, 3, activation='relu', padding='same')(x) y = layers.Conv2D(128, 3, activation='relu', padding='same')(y) y = layers.MaxPooling2D(2, strides=2)(y) residual = layers.Conv2D(128, 1, strides=2, padding='same')(x) # 使用1*1的卷積,將原始張量線性下采樣為y具有相同的形狀 y = layers.add([y, residual]) # 將原始x與輸出特征相加
2、權重共享
即多次調用同一個實例
# coding: utf-8 """函數式子API:權重共享 能夠重復的使用同一個實例,這樣相當于重復使用一個層的權重,不需要重新編寫""" from keras import layers from keras import Input from keras.models import Model lstm = layers.LSTM(32) # 實例化一個LSTM層,后面被調用很多次 # ------------------------左邊分支-------------------------------- left_input = Input(shape=(None, 128)) left_output = lstm(left_input) # 調用lstm實例 # ------------------------右分支--------------------------------- right_input = Input(shape=(None, 128)) right_output = lstm(right_input) # 調用lstm實例 # ------------------------將層進行連接合并------------------------ merged = layers.concatenate([left_output, right_output], axis=-1) # -----------------------在上面構建一個分類器--------------------- predictions = layers.Dense(1, activation='sigmoid')(merged) # -------------------------構建模型,并擬合訓練----------------------------------- model = Model([left_input, right_input], predictions) model.fit([left_data, right_data], targets)
感謝你能夠認真閱讀完這篇文章,希望小編分享keras實現多種分類網絡的方法內容對大家有幫助,同時也希望大家多多支持億速云,關注億速云行業資訊頻道,遇到問題就找億速云,詳細的解決方法等著你來學習!
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