keras源码engine中toplogy.py定义了加载权重的函数:
load_weights(self, filepath, by_name=False)
其中默认by_name为False,这时候加载权重按照网络拓扑结构加载,适合直接使用keras中自带的网络模型,如VGG16
VGG19/resnet50等,源码描述如下:
If `by_name` is False (default) weights are loaded
based on the network's topology, meaning the architecture
should be the same as when the weights were saved.
Note that layers that don't have weights are not taken
into account in the topological ordering, so adding or
removing layers is fine as long as they don't have weights.
若将by_name改为True则加载权重按照layer的name进行,layer的name相同时加载权重,适合用于改变了
模型的相关结构或增加了节点但利用了原网络的主体结构情况下使用,源码描述如下:
If `by_name` is True, weights are loaded into layers
only if they share the same name. This is useful
for fine-tuning or transfer-learning models where
some of the layers have changed.
在进行边缘检测时,利用VGG网络的主体结构,网络中增加反卷积层,这时加载权重应该使用
model.load_weights(filepath,by_name=True)
补充知识:Keras下实现mnist手写数字
之前一直在用tensorflow,被同学推荐来用keras了,把之前文档中的mnist手写数字数据集拿来练手,
代码如下。
import struct import numpy as np import os import keras from keras.models import Sequential from keras.layers import Dense from keras.optimizers import SGD def load_mnist(path, kind): labels_path = os.path.join(path, '%s-labels.idx1-ubyte' % kind) images_path = os.path.join(path, '%s-images.idx3-ubyte' % kind) with open(labels_path, 'rb') as lbpath: magic, n = struct.unpack('>II', lbpath.read(8)) labels = np.fromfile(lbpath, dtype=np.uint8) with open(images_path, 'rb') as imgpath: magic, num, rows, cols = struct.unpack(">IIII", imgpath.read(16)) images = np.fromfile(imgpath, dtype=np.uint8).reshape(len(labels), 784) #28*28=784 return images, labels #loading train and test data X_train, Y_train = load_mnist('.\\data', kind='train') X_test, Y_test = load_mnist('.\\data', kind='t10k') #turn labels to one_hot code Y_train_ohe = keras.utils.to_categorical(Y_train, num_classes=10) #define models model = Sequential() model.add(Dense(input_dim=X_train.shape[1],output_dim=50,init='uniform',activation='tanh')) model.add(Dense(input_dim=50,output_dim=50,init='uniform',activation='tanh')) model.add(Dense(input_dim=50,output_dim=Y_train_ohe.shape[1],init='uniform',activation='softmax')) sgd = SGD(lr=0.001, decay=1e-7, momentum=0.9, nesterov=True) model.compile(loss='categorical_crossentropy', optimizer=sgd, metrics=["accuracy"]) #start training model.fit(X_train,Y_train_ohe,epochs=50,batch_size=300,shuffle=True,verbose=1,validation_split=0.3) #count accuracy y_train_pred = model.predict_classes(X_train, verbose=0) train_acc = np.sum(Y_train == y_train_pred, axis=0) / X_train.shape[0] print('Training accuracy: %.2f%%' % (train_acc * 100)) y_test_pred = model.predict_classes(X_test, verbose=0) test_acc = np.sum(Y_test == y_test_pred, axis=0) / X_test.shape[0] print('Test accuracy: %.2f%%' % (test_acc * 100))
训练结果如下:
Epoch 45/50 42000/42000 [==============================] - 1s 17us/step - loss: 0.2174 - acc: 0.9380 - val_loss: 0.2341 - val_acc: 0.9323 Epoch 46/50 42000/42000 [==============================] - 1s 17us/step - loss: 0.2061 - acc: 0.9404 - val_loss: 0.2244 - val_acc: 0.9358 Epoch 47/50 42000/42000 [==============================] - 1s 17us/step - loss: 0.1994 - acc: 0.9413 - val_loss: 0.2295 - val_acc: 0.9347 Epoch 48/50 42000/42000 [==============================] - 1s 17us/step - loss: 0.2003 - acc: 0.9413 - val_loss: 0.2224 - val_acc: 0.9350 Epoch 49/50 42000/42000 [==============================] - 1s 18us/step - loss: 0.2013 - acc: 0.9417 - val_loss: 0.2248 - val_acc: 0.9359 Epoch 50/50 42000/42000 [==============================] - 1s 17us/step - loss: 0.1960 - acc: 0.9433 - val_loss: 0.2300 - val_acc: 0.9346 Training accuracy: 94.11% Test accuracy: 93.61%
以上这篇keras导入weights方式就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持呐喊教程。
声明:本文内容来源于网络,版权归原作者所有,内容由互联网用户自发贡献自行上传,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任。如果您发现有涉嫌版权的内容,欢迎发送邮件至:notice#nhooo.com(发邮件时,请将#更换为@)进行举报,并提供相关证据,一经查实,本站将立刻删除涉嫌侵权内容。