基于KNN模型的层次纠错输出编码算法

纠错输出编码是一种解决多类分类问题的有效方法,但其编码矩阵只对类进行编码且都采用事先构造出来的统一形式,适应性较差。为此,提出一种新颖的层次纠错输出编码算法。该算法在训练阶段先通过KNN模型算法在数据集上构建多个同类簇,选取各类中最具代表性的簇形成层次编码矩阵,然后再根据编码矩阵进行单分类器训练。在测试阶段,该算法通过模型融合进一步发挥KNN模型和纠错输出编码各自的优点。在UCI公共数据集上的实验结果表明,新方法的性能优于KNN模型算法和纠错输出编码算法。     

基于最小k 近邻错分率编码确定方法及其在多类分类中的应用

构造输出编码矩阵是将多类分类问题分解为多个两类分类问题的有效方法之一,如何判断一个编码阵的好坏是此类问题的关键．提出以最小庇近邻错分率作为评价标准,把构造问题简化为一个搜索问题．在M类的所有二类划分空间中,通过行交换规则和有限启发式搜索策略搜索出南近邻错分率最小的l个二类划分,并依据编码规则得到最终输出编码矩阵．实验中用人工数据集和UCI数据集分别测试,通过与几种经典的编码方法比较,结果表明该编码方法能在编码长度较小情况下得到更好的分类效果．     

基于纠错输出编码的多类概率建模

目前模式识别领域中缺乏有效的多类概率建模方法,对此提出利用纠错输出编码作为多类概率建模框架,将二元纠错输出编码研究的概率输出问题转化为线性超定方程的求解问题,通过线性最小二乘法来求解并获取多类后验概率的结果;而对于三元纠错输出编码的等价非线性超定方程组,提出一种迭代法则来求解多类概率输出.实验中通过与3种经典方法相比较可以发现,新方法求取的概率输出具有更好的分布形态,并且该方法具有较好的分类性能.     

基于最小二乘和纠错输出编码的多类分类

多类分类是目标识别中必须面对的一个关键问题,现有分类器大都为二分器,无法满足对多类目标进行分类,为此,提出利用纠错输出编码方法对多类问题进行分解,即把多类问题转化成二类问题;同时讨论一种基于最小二乘法对二分器结果进行融合的策略。实验分别对UCI数据集和三种一维距离像数据集进行测试,结果表明与经典的多分类器相比,提出的多类分类策略有较高的分类正确率。     

一种基于支持向量机的人脸识别新方法

关于人脸识别问题,采用一种基于独立分量分析进行特征提取和支持向量机实现多分类的人脸识别新方法.根据支持向量机理论,为提高对人脸的识别率,提出环形对称划分的支持向量机多分类算法.算法将多类问题的类别环形排列,依次进行对称划分构造纠错编码输出矩阵;根据求得的纠错编码输出矩阵,用解码函数求解待求样本的类别.对于人脸识别问题,利用独立分量分析方法构造人脸的特征脸空间,在特征脸空间运用算法进行人脸识别,在人脸数据库上的仿真结果表明,算法能有效地完成人脸识别任务.     

基于子类划分和粒子群优化的自适应编码多类分类方法

纠错输出编码(ECOC)可以有效地解决多类分类问题.基于数据的编码是主要的编码方法之一.对此,提出一种基于子类划分和粒子群优化(PSO)的自适应编码方法,利用混淆矩阵衡量各类别的相关性,基于规则的方法对类别进行自适应组合,根据组合方案构建类别的二类划分并最终形成编码矩阵,通过引入PSO算法寻找最优阈值,从而得到最优编码矩阵.实验结果表明,所提出的编码方法可以得到更好的分类性能.     

半监督层次纠错输出编码算法

纠错输出编码是一种处理多类分类问题的有效方法,但它只能用于有监督的数据,而对大量未标签样本却无法利用.提出一种新颖的基于半监督技术的层次编码算法,对传统的纠错输出编码算法(ECOC)进行改造,拓展了编码的概念.在编码阶段,根据簇特征进行同类组合后再进行层次编码,从而在充分利用了无标签样本的同时,根据数据类分布的特点进行编码以提高算法精度.最后在化工产品有毒性预测数据集上的实验结果表明了本方法的可行性和有效性.     

基于特征空间变换的纠错输出编码

针对基于纠错输出编码多类分类中如何保证基分类器差异性的问题, 提出一种基于特征空间变换的编码方法. 该方法引入特征空间, 将编码矩阵扩展成三维矩阵; 然后基于二类划分, 利用特征变换得到不同的特征子空间, 从而训练得到差异性大的基分类器. 基于公共数据集的实验结果表明: 该方法能够比原始的编码矩阵获得更优的分类性能, 同时增加了基分类器的差异性; 该方法适用于任何编码矩阵, 为大数据的分类提供了新的思路.

     

基于纠错输出编码的人脸表情识别

多分类问题一直是模式识别领域的一个热点,提出了一种基于纠错输出编码和支持向量机的多分类器算法。根据通信编码理论设计纠错输出编码矩阵;按照该编码矩阵设计若干个互不相关的子支持向量机,根据编码原理将它们融合为一个多分类器。为了验证本分类器的有效性,采用Gabor小波提取人脸表情特征,应用二元主成分（2DPCA）分析法对提取的特征进行降维处理,应用该分类器进行了人脸表情的识别。实验结果表明,提出的方法能有效提高人脸表情的识别率,并具有极好的鲁棒性。     

基于AUC方法评估多类别贝叶斯分类器的性能

分类器评估一般采用准确性评估.理论证明,基于AUC方法评估分类器优于准确性评估方法,但该方法局限于二类分类问题.提出一种将二类分类问题推广到多类分类问题的新方法,用纠错输出码转换得到转换矩阵,通过转换矩阵把多类分类问题转换成二类分类问题,计算二类分类的平均值来评估分类器的性能.新方法在MBNC实验平台下编程实现,并评估贝叶斯分类器的性能,实验结果表明,这种方法是有效的.     

Traffic sign recognition system with β -correction

Traffic sign classification represents a classical application of multi-object recognition processing in uncontrolled adverse environments. Lack of visibility, illumination changes, and partial occlusions are just a few problems. In this paper, we introduce a novel system for multi-class classification of traffic signs based on error correcting output codes (ECOC). ECOC is based on an ensemble of binary classifiers that are trained on bi-partition of classes. We classify a wide set of traffic signs types using robust error correcting codings. Moreover, we introduce the novel β-correction decoding strategy that outperforms the state-of-the-art decoding techniques, classifying a high number of classes with great success.     

Coding and decoding strategies for multi-class learning problems

It is known that the error correcting output code (ECOC) technique, when applied to multi-class learning problems, can improve generalisation performance. One reason for the improvement is its ability to decompose the original problem into complementary two-class problems. Binary classifiers trained on the sub-problems are diverse and can benefit from combining using a simple distance-based strategy. However there is some discussion about why ECOC performs as well as it does, particularly with respect to the significance of the coding/decoding strategy. In this paper we consider the binary (0,1) code matrix conditions necessary for reduction of error in the ECOC framework, and demonstrate the desirability of equidistant codes. It is shown that equidistant codes can be generated by using properties related to the number of 1’s in each row and between any pair of rows. Experimental results on synthetic data and a few popular benchmark problems show how performance deteriorates as code length is reduced for six decoding strategies.     

支持向量机多类分类方法

支持向量机本身是一个两类问题的判别方法，不能直接应用于多类问题。当前针对多类问题的支持向量机分类方法主要有5种：一类对余类法（OVR），一对一法（OVO），二叉树法（BT），纠错输出编码法和有向非循环图法。本文对这些方法进行了简单的介绍，通过对其原理和实现方法的分析，从速度和精度两方面对这些方法的优缺点进行了归纳和总结，给出了比较意见，并通过实验进行了验证，最后提出了一些改进建议。     

An incremental node embedding technique for error correcting output codes

The error correcting output codes (ECOC) technique is a useful way to extend any binary classifier to the multiclass case. The design of an ECOC matrix usually considers an a priori fixed number of dichotomizers. We argue that the selection and number of dichotomizers must depend on the performance of the ensemble code in relation to the problem domain. In this paper, we present a novel approach that improves the performance of any initial output coding by extending it in a sub-optimal way. The proposed strategy creates the new dichotomizers by minimizing the confusion matrix among classes guided by a validation subset. A weighted methodology is proposed to take into account the different relevance of each dichotomizer. As a result, overfitting is avoided and small codes with good generalization performance are obtained. In the decoding step, we introduce a new strategy that follows the principle that positions coded with the symbol zero should have small influence in the results. We compare our strategy to other well-known ECOC strategies on the UCI database, and the results show it represents a significant improvement.     

Research on the unbiased probability estimation of error-correcting output coding

Supervised classification based on error-correcting output codes (ECOC) is an efficient method to solve the problem of multi-class classification, and how to get the accurate probability estimation via ECOC is also an attractive research direction. This paper proposed three kinds of ECOC to get unbiased probability estimates, and investigated the corresponding classification performance in depth at the same time. Two evaluating criterions for ECOC that has better classification performance were concluded, which are Bayes consistence and unbiasedness of probability estimation. Experimental results on artificial data sets and UCI data sets validate the correctness of our conclusion.     

On the Decoding Process in Ternary Error-Correcting Output Codes

A common way to model multiclass classification problems is to design a set of binary classifiers and to combine them. Error-Correcting Output Codes (ECOC) represent a successful framework to deal with these type of problems. Recent works in the ECOC framework showed significant performance improvements by means of new problem-dependent designs based on the ternary ECOC framework. The ternary framework contains a larger set of binary problems because of the use of a “do not care” symbol that allows us to ignore some classes by a given classifier. However, there are no proper studies that analyze the effect of the new symbol at the decoding step. In this paper, we present a taxonomy that embeds all binary and ternary ECOC decoding strategies into four groups. We show that the zero symbol introduces two kinds of biases that require redefinition of the decoding design. A new type of decoding measure is proposed, and two novel decoding strategies are defined. We evaluate the state-of-the-art coding and decoding strategies over a set of UCI Machine Learning Repository data sets and into a real traffic sign categorization problem. The experimental results show that, following the new decoding strategies, the performance of the ECOC design is significantly improved.     

一种适用于多类不平衡数据集的模糊关联分类方法

提出一种适用于多类不平衡分布情形下的模糊关联分类方法,该方法以最小化AdaBoost.M1W集成学习迭代过程中训练样本的加权分类错误率和子分类器中模糊关联分类规则数目及规则中所含模糊项的数目为遗传优化目标,实现了AdaBoost.M1W和模糊关联分类建模过程的较好融合.通过5个多类不平衡UCI标准数据集和现有的针对不平衡分类问题的数据预处理方法实验对比结果,表明了所提出的方法能显著提高多类不平衡情形下的模糊关联分类模型的分类性能.