基于类别分布差异和VPRS特征选择的文本分类方法

权值计算和特征降维是影响文本分类的精度和效率的两个重要步骤。该文首先根据特征词的类别分布差异进行特征过滤；然后，分析传统的权值公式TF-IDF的缺点，采用改进的权值计算公式简记为TF-CDF，依据TF-CDF公式计算每个特征词的权值，生成文档集的向量空间模型VSM；接着，提出了一种基于可变精度粗糙理论(VPRS)的特征选择进一步选择对分类贡献度大的特征，并用SQL实现。最后利用支持向量机LibSVM分类器进行实验，实验结果表明特征过滤和选择方法及TF-CDF权值公式有助于提高分类精度和分类效率。

Feature Selection Based on Class Distribution Difference and VPRS for Text Classification

Weight calculating and feature reduction are key preprocesses in text classification.Firstly,those useless to classify texts are filtered according the category document frequency distribution difference of each feature;and then in order to overcome the limitations of TF-IDF weighting formula a novel weighting formula called TF-CDF is presented.Calculate the weight of each feature according to TF-CDF and build the Vector Space Model(VSM) for the entire corpus.To select significant features,a feature selection approach based on Variable Precision Rough Set(VPRS) is also proposed and implement with some SQL sentences combining the definitions of VPRS with the advantages of SQL sentences.Finally,some experiments based on different weighting formulas and feature selection methods are conducted using libSVM as text classifier.The experimental results show that the novel feature filtering,weighting formula and feature selection method improve the performance of text classification.