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Browsing by Author "Van der Walt, Christiaan M"

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Data characteristics that determine classifier performance

Author: Van der Walt, Christiaan M ; Barnard, E Date: Nov 2006 The relationship between the distribution of data, on the one hand, and classifier performance, on the other, for non-parametric classifiers has been studied. It is shown that predictable factors such as the available amount of training data ... Read more
Density estimation from local structure

Author: Van der Walt, Christiaan M ; Barnard, E Date: Nov 2009 The authors propose a hyper-ellipsoid clustering algorithm that grows clusters from local structures in a dataset and estimates the underlying geometrical structure of data with a set of hyper-ellipsoids. The clusters are used to estimate a ... Read more
Learning structured representations of data

Author: Barnard, E ; Van der Walt, Christiaan M ; Davel, M ; Van Heerden, C ; Senekal, FP ; Naidoo, T Date: Nov 2009 Bayesian networks have shown themselves to be useful tools for the analysis and modelling of large data sets. However, their complete generality leads to computational and modelling complexities that have limited their applicability. We propose ... Read more
Low default credit scoring using two-class non-parametric kernel density estimation

Author: Rademeyer, E ; Van der Walt, Christiaan M ; De Waal, A Date: Dec 2016 This paper investigates the performance of two-class classification credit scoring data sets with low default ratios. The standard two-class parametric Gaussian and non-parametric Parzen classifiers are extended, using Bayes’ rule, to include ... Read more
Measures for the characterisation of pattern-recognition data sets

Author: Van der Walt, Christiaan M ; Barnard, E Date: Nov 2007 The authors study the relationship between the properties of data and classifier performance. Data measures are employed to characterise classification problems and it is shown that these data measures successfully capture important characteristics ... Read more
Optimizing tree-species classification in hyperspectal images

Author: Barnard, E ; Cho, Moses A ; Debba, Pravesh ; Mathieu, Renaud SA ; Wessels, Konrad J ; van Heerden, C ; Van der Walt, Christiaan M ; Asner, GP Date: Nov 2010 The authors investigate the classification of eight prominent savanna tree species, based on hyperspectral reflectance data. Although two principal components account for 95% of the variance of the data, up to 20 components are found to be ... Read more
Variable kernel density estimation in high-dimensional feature spaces

Author: Van der Walt, Christiaan M ; Barnard, E Date: Feb 2017 Estimating the joint probability density function of a dataset is a central task in many machine learning applications. In this work we address the fundamental problem of kernel bandwidth estimation for variable kernel density estimation in ... Read more

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Browsing by Author "Van der Walt, Christiaan M"

Browsing by Author "Van der Walt, Christiaan M"

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All of ResearchSpace

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