学习核分类器:理论与算法概述

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"Herbrich的《Learning Kernel Classifiers: Theory and Algorithms》是关于机器学习领域内核方法的一本重要著作,由麻省理工学院出版社出版。这本书深入探讨了使用核函数进行分类的理论基础与算法实现,由Adaptive Computation and Machine Learning系列的主编Thomas G. Dietterich以及几位知名学者共同编辑。书中的内容涵盖了多个相关主题,如强化学习、图形模型、数据挖掘等,旨在提供一个全面的视角来理解和支持向量机(SVM)、核方法在优化和泛化能力上的应用。作者Ralf Herbrich是这个领域的专家,他的工作对理解和实践基于核的学习算法有重大贡献。书中可能涉及了如何利用核技巧来构建高效的学习模型,以及如何解决非线性可分问题。此外,可能还讨论了正则化、贝叶斯网络、因果推断等相关理论,并且提供了实际应用案例和算法分析。" 该书与其他著名学者的作品一起,如Pierre Baldi和Søren Brunak的《Bioinformatics: The Machine Learning Approach》,Richard S. Sutton和Andrew G. Barto的《Reinforcement Learning: An Introduction》,以及Bernhard Schölkopf和Alexander J. Smola的《Learning with Kernels: Support Vector Machines, Regularization, Optimization, and Beyond》,共同构成了对机器学习,特别是核方法的深入研究。这些书籍共同揭示了机器学习领域的核心概念和技术,对于想要深化对这一领域的理解的学者和实践者来说是宝贵的资源。 通过阅读《Learning Kernel Classifiers: Theory and Algorithms》,读者可以期待掌握如何利用核方法设计和训练有效的分类器,理解其背后的数学原理,以及如何在实际问题中应用这些理论。同时,这本书也可能引导读者思考如何结合其他机器学习技术,如图形模型和强化学习,来增强学习性能和模型的解释性。这本书为读者提供了一个深入探索机器学习中核方法的理论和实践的窗口。

class MSMDAERNet(nn.Module): def init(self, pretrained=False, number_of_source=15, number_of_category=4): super(MSMDAERNet, self).init() self.sharedNet = pretrained_CFE(pretrained=pretrained) # for i in range(1, number_of_source): # exec('self.DSFE' + str(i) + '=DSFE()') # exec('self.cls_fc_DSC' + str(i) + '=nn.Linear(32,' + str(number_of_category) + ')') for i in range(number_of_source): exec('self.DSFE' + str(i) + '=DSFE()') exec('self.cls_fc_DSC' + str(i) + '=nn.Linear(32,' + str(number_of_category) + ')') def forward(self, data_src, number_of_source, data_tgt=0, label_src=0, mark=0): ''' description: take one source data and the target data in every forward operation. the mmd loss is calculated between the source data and the target data (both after the DSFE) the discrepency loss is calculated between all the classifiers' results (test on the target data) the cls loss is calculated between the ground truth label and the prediction of the mark-th classifier 之所以target data每一条线都要过一遍是因为要计算discrepency loss, mmd和cls都只要mark-th那条线就行 param {type}: mark: int, the order of the current source data_src: take one source data each time number_of_source: int label_Src: corresponding label data_tgt: target data return {type} ''' mmd_loss = 0 disc_loss = 0 data_tgt_DSFE = [] if self.training == True: # common feature extractor data_src_CFE = self.sharedNet(data_src) data_tgt_CFE = self.sharedNet(data_tgt) # Each domian specific feature extractor # to extract the domain specific feature of target data for i in range(number_of_source): DSFE_name = 'self.DSFE' + str(i) data_tgt_DSFE_i = eval(DSFE_name)(data_tgt_CFE) data_tgt_DSFE.append(data_tgt_DSFE_i) # Use the specific feature extractor # to extract the source data, and calculate the mmd loss DSFE_name = 'self.DSFE' + str(mark) data_src_DSFE = eval(DSFE_name)(data_src_CFE) # mmd_loss += utils.mmd(data_src_DSFE, data_tgt_DSFE[mark]) mmd_loss += utils.mmd_linear(data_src_DSFE, data_tgt_DSFE[mark]) # discrepency loss for i in range(len(data_tgt_DSFE)): if i != mark: disc_loss += torch.mean(torch.abs( F.softmax(data_tgt_DSFE[mark], dim=1) - F.softmax(data_tgt_DSFE[i], dim=1) )) # domain specific classifier and cls_loss DSC_name = 'self.cls_fc_DSC' + str(mark) pred_src = eval(DSC_name)(data_src_DSFE) cls_loss = F.nll_loss(F.log_softmax( pred_src, dim=1), label_src.squeeze()) return cls_loss, mmd_loss, disc_loss中data_tgt_DSFE的长度

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