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1.
分类在数据挖掘中扮演着很重要的角色,然而单个分类器有很多缺点,包括适用范围十分有限和分类准确度不高等。把多个单分类器的分类结果融合起来是克服这些缺点的有效途径,因此存在很高的研究价值。组合多分类器的一个核心内容是融合规则,现存的融合规则有积规则、和规则、中值规则与投票规则等,但这些规则性能还不够稳定。提出了一个新的基于神经网络的融合规则,并依此建立一个新的多分类器组合模型,实验表明它能提高分类准确度和稳定性。  相似文献   

2.
模糊控制是基于领域专家所给出的模糊控制规则来实现对系统的控制,这些模糊控制规则粗略地描述了控制器输入和输出之间的关系.模糊控制采用的是一种分段逼近的思想,因此在对高阶和多输入等实际复杂系统控制过程中,模糊控制存在控制规则组合爆炸和控制精度不高两大问题.从常规二维模糊控制器的输入变量误差E和误差变化率EC的基本物理意义出发,深入分析它们之间所蕴含的逻辑关系,指出这种关系的本质就是泛逻辑学中的泛组合关系,可用简单的泛组合运算代替复杂的模糊规则推理过程.据此提出了一种柔性逻辑控制方法,可实现对复杂系统的精确控制.最后,一级倒立摆的实物实验结果证明了该方法的可行性和有效性.  相似文献   

3.
基于AdaBoost的组合分类器在遥感影像分类中的应用*   总被引:2,自引:0,他引:2  
运用组合分类器的经典算法AdaBoost将多个弱分类器-神经网络分类器组合输出,并引入混合判别多分类器综合规则,有效提高疑难类别的分类精度,进而提高分类的总精度.最后以天津地区ASTER影像为例,介绍了基于AdaBoost的组合分类算法,并在此基础上实现了天津地区的土地利用分类.分类结果表明,组合分类器能有效提高单个分类器的分类精度,分类总精度由81.13%提高到93.32%.实验表明基于AdaBoost的组合分类是遥感图像分类的一种新的有效方法.  相似文献   

4.
本文介绍了一类可用于分类器融合的泛组合逻辑算子,同时作为方法论基础研究了基于案例学习的泛逻辑运算符(算子)构造和选择方法,并以此构造分类器的融合器,实验数据集选择了UCI的spam数据集,并同其他融合方法进行了对比。结果表明本文所述方法具有较低的错误率和相应较高的查全率。  相似文献   

5.
提出了一种手写体数字识别系统.该系统由三级分类器组成第一级提取交叉点、闭和圆等结构特征,并用模板匹配的方法进行分类;第二级由两个并行的神经网络分类器组成,每个分类器分别使用不同的统计特征;第三级是综合分类器,它将第二级的输出作为输入,根据投票规则得到最后的输出结果.多分类器组合可以集合分类器的优点,提高整个识别系统的识别精度和可靠性.  相似文献   

6.
多分类器组合及其应用   总被引:5,自引:0,他引:5  
1 引言传统的模式识别系统通常只使用样本的某种单一特征描述和特定的一个分类器来进行分类。这种系统对于类别数较大、输入样本带噪声的问题很难获得好的分类效果。近来发现不同的特征描述、不同的分类器在分类性能上存在着彼此互补的现象,因此同时使用多种特征描述和多个分类器可能提高分类精确性。目前,多分类器组合的研究吸引了学者们广泛的注意,并  相似文献   

7.
针对通信信号非稳定、信噪比(SNR)变化范围大的特性,利用调制信号的循环平稳特性,提取出五种对SNR和信号调制参数不敏感但对调制类型敏感的特征参量。为提高分类性能,设计了一种采用多个不同神经网络的组合分类器结构,采用输出向量加权表决的融合规则。仿真表明,低信噪比下组合神经网络分类器比单个神经网络分类器有更高的识别率。  相似文献   

8.
提出了一种使用基于规则的基分类器建立组合分类器的新方法PCARules。尽管新方法也采用基分类器预测的加权投票来决定待分类样本的类,但是为基分类器创建训练数据集的方法与bagging和boosting完全不同。该方法不是通过抽样为基分类器创建数据集,而是随机地将特征划分成K个子集,使用PCA得到每个子集的主成分,形成新的特征空间,并将所有训练数据映射到新的特征空间作为基分类器的训练集。在UCI机器学习库的30个随机选取的数据集上的实验表明:算法不仅能够显著提高基于规则的分类方法的分类性能,而且与bagging和boosting等传统组合方法相比,在大部分数据集上都具有更高的分类准确率。  相似文献   

9.
多分类器组合是提高识别效果的一条有效途径。文中提出一种用于多分类器组合的改进贝叶斯规则,即首先通过对大量样本的统计获得有关每个分类器识别性能的先验知识,将其作为多分类器组合的依据。组合时对每个类设置不同的阈值,使组合效果得以改善,这些阈值可以通过训练获得。在数字识别中的应用结果表明,改进的贝叶斯规则可以使多分类器的组合结果识别率和置信度得到明显提高。  相似文献   

10.
分类器线性组合的有效性和最佳组合问题的研究   总被引:8,自引:0,他引:8  
通过多个分类器的组合来提升分类精度是机器学习领域主要研究内容,弱学习定理保证了这种研究的可行性.分类器的线性组合,也即加权投票.是最常用的组合方法,其中广泛使用的AdaBoost算法和Bagging算法就是采取的加权投票.分类器组合的有效性问题以及最佳组合问题均需要解决.在各单个分类器互不相关和分类器数量较多条件下,得到了分类器组合有效的组合系数选取条件以及最佳组合系数公式,给出了组合分类器的误差分析.结论表明,当各分类器分类错误率有统一的边界时,即使采取简单投票,也能确保组合分类器分类错误率随分类器个数增加而以指数级降低.在此基础上,仿照AdaBoost算法,提出了一些新的集成学习算法.特别是提出了直接面向组合分类器分类精度快速提升这一目标的集成学习算法.分析并指出了这种算法的合理性和科学性.它是对传统的以错误率最低为目标的分类器训练与选取方法的延伸和扩展.从另一个角度证明了AdaBOOSt算法中采用的组合不仅有效.而且在一定条件下等效于最佳组合.针对多分类问题.得到了与二分类问题类似的分类器组合理论与结论.包括组合有效条件、最佳组合、误差估计等.还对AdaBoOSt算法进行了一定的扩展.  相似文献   

11.
This paper investigates the effects of confidence transformation in combining multiple classifiers using various combination rules. The combination methods were tested in handwritten digit recognition by combining varying classifier sets. The classifier outputs are transformed to confidence measures by combining three scaling functions (global normalization, Gaussian density modeling, and logistic regression) and three confidence types (linear, sigmoid, and evidence). The combination rules include fixed rules (sum-rule, product-rule, median-rule, etc.) and trained rules (linear discriminants and weighted combination with various parameter estimation techniques). The experimental results justify that confidence transformation benefits the combination performance of either fixed rules or trained rules. Trained rules mostly outperform fixed rules, especially when the classifier set contains weak classifiers. Among the trained rules, the support vector machine with linear kernel (linear SVM) performs best while the weighted combination with optimized weights performs comparably well. I have also attempted the joint optimization of confidence parameters and combination weights but its performance was inferior to that of cascaded confidence transformation-combination. This justifies that the cascaded strategy is a right way of multiple classifier combination.  相似文献   

12.
In classifier combination, the relative values of beliefs assigned to different hypotheses are more important than accurate estimation of the combined belief function representing the joint observation space. Because of this, the independence requirement in Dempster’s rule should be examined from classifier combination point of view. In this study, it is investigated whether there is a set of dependent classifiers which provides a better combined accuracy than independent classifiers when Dempster’s rule of combination is used. The analysis carried out for three different representations of statistical evidence has shown that the combination of dependent classifiers using Dempster’s rule may provide much better combined accuracies compared to independent classifiers.  相似文献   

13.
Due to the wide variety of fusion techniques available for combining multiple classifiers into a more accurate classifier, a number of good studies have been devoted to determining in what situations some fusion methods should be preferred over other ones. However, the sample size behavior of the various fusion methods has hitherto received little attention in the literature of multiple classifier systems. The main contribution of this paper is thus to investigate the effect of training sample size on their relative performance and to gain more insight into the conditions for the superiority of some combination rules.A large experiment is conducted to study the performance of some fixed and trainable combination rules for executing one- and two-level classifier fusion for different training sample sizes. The experimental results yield the following conclusions: when implementing one-level fusion to combine homogeneous or heterogeneous base classifiers, fixed rules outperform trainable ones in nearly all cases, with only one exception of merging heterogeneous classifiers for large sample size. Moreover, the best classification for any considered sample size is generally achieved by a second level of combination (namely, utilizing one fusion rule to further combine a set of ensemble classifiers with each of them constructed by fusing base classifiers). Under these circumstances, it seems that adopting different types of fusion rules (fixed or trainable) as the combiners for two levels of fusion is appropriate.  相似文献   

14.
多分类器组合研究   总被引:2,自引:0,他引:2  
文章提出了一种多分类器的组合方法,它利用了参与组合的分类器提供的度量层次上的两类信息:对训练样本的决策信息;对待识样本的决策信息。首先对这两类信息进行集成,进而给出了组合分类器的判定规则。用该方法对手写体汉字作分类识别,实验结果显示,较之其它几种方法,它有更高的正确识别率。  相似文献   

15.
用基于遗传算法的全局优化技术动态地选择一组分类器,并根据应用的背景,采用合适的集成规则进行集成,从而综合了不同分类器的优势和互补性,提高了分类性能。实验结果表明,通过将遗传算法引入到多分类器集成系统的设计过程,其分类性能明显优于传统的单分类器的分类方法。  相似文献   

16.
提出了一种基于Borda规则的分类器组合方法。该方法将分类器组合问题看成多目标多人决策问题,是一种基于类别排序的方法。在标准手写数字数据集上对该算法进行了实验研究,证实该算法的识别率较单个分类器有明显提高,具有深入研究的价值。  相似文献   

17.
When combining outputs from multiple classifiers, many combination rules are available. Although easy to implement, fixed combination rules are optimal only in restrictive conditions. We discuss and evaluate their performance when the optimality conditions are not fulfilled. Fixed combination rules are then compared with trainable combination rules on real data in the context of face-based identity verification. The face images are classified by combining the outputs of five different face verification experts. It is demonstrated that a reduction in the error rates of up to 50% over the best single expert is achieved on the XM2VTS database, using either fixed or trainable combination rules.  相似文献   

18.
How to effectively predict financial distress is an important problem in corporate financial management. Though much attention has been paid to financial distress prediction methods based on single classifier, its limitation of uncertainty and benefit of multiple classifier combination for financial distress prediction has also been neglected. This paper puts forward a financial distress prediction method based on weighted majority voting combination of multiple classifiers. The framework of multiple classifier combination system, model of weighted majority voting combination, basic classifiers’ voting weight model and basic classifiers’ selection principles are discussed in detail. Empirical experiment with Chinese listed companies’ real world data indicates that this method can greatly improve the average prediction accuracy and stability, and it is more suitable for financial distress prediction than single classifiers.  相似文献   

19.
Generalized rules for combination and joint training of classifiers   总被引:1,自引:0,他引:1  
Classifier combination has repeatedly been shown to provide significant improvements in performance for a wide range of classification tasks. In this paper, we focus on the problem of combining probability distributions generated by different classifiers. Specifically, we present a set of new combination rules that generalize the most commonly used combination functions, such as the mean, product, min, and max operations. These new rules have continuous and differentiable forms, and can thus not only be used for combination of independently trained classifiers, but also as objective functions in a joint classifier training scheme. We evaluate both of these schemes by applying them to the combination of phone classifiers in a speech recognition system. We find a significant performance improvement over previously used combination schemes when jointly training and combining multiple systems using a generalization of the product rule.  相似文献   

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