arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1601.01944stat.MLcs.LG
收藏

类比例的非参数半监督学习

Nonparametric semi-supervised learning of class proportions

Indiana University(印第安纳大学)

Shantanu Jain, Martha White, Michael W. Trosset, Predrag Radivojac

摘要:

在机器学习中,经常会遇到从正的和未标记的数据开发二进制分类器的问题。在这种情况下,一个常见的要求是近似后验概率的积极和消极的类为以前看不见的数据点。这个问题可以分解成两个步骤:(i)准确的预测,区分阳性和未标记的数据,(ii)准确估计的先验概率的阳性和阴性的例子之间的发展。在这项工作中,我们主要集中在后者的子问题。我们研究非参数类先验估计,并制定这个问题作为一个估计的混合比例在两个组件的混合模型,给定一个样本的组件和另一个样本的混合物本身。我们发现,混合比例的估计一般是不明确的,并提出了一个规范形式,以获得可识别性,同时保持灵活性,以模拟任何分布。我们使用的见解,从这个理论来阐明类先验的优化表面,并提出了一个算法来估计它们。为了解决高维密度估计的问题,我们提供了实用的转换到低维空间,保持类先验。最后,我们证明了我们的方法对单变量和多变量数据的有效性。

英文摘要:

The problem of developing binary classifiers from positive and unlabeled data is often encountered in machine learning. A common requirement in this setting is to approximate posterior probabilities of positive and negative classes for a previously unseen data point. This problem can be decomposed into two steps: (i) the development of accurate predictors that discriminate between positive and unlabeled data, and (ii) the accurate estimation of the prior probabilities of positive and negative examples. In this work we primarily focus on the latter subproblem. We study nonparametric class prior estimation and formulate this problem as an estimation of mixing proportions in two-component mixture models, given a sample from one of the components and another sample from the mixture itself. We show that estimation of mixing proportions is generally ill-defined and propose a canonical form to obtain identifiability while maintaining the flexibility to model any distribution. We use insights from this theory to elucidate the optimization surface of the class priors and propose an algorithm for estimating them. To address the problems of high-dimensional density estimation, we provide practical transformations to low-dimensional spaces that preserve class priors. Finally, we demonstrate the efficacy of our method on univariate and multivariate data.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑