• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • Tagged with
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Contribui??es aos Processos de Clustering com Base em M?tricas n?o-Euclidianas

Martins, Allan de Medeiros 08 March 2005 (has links)
Made available in DSpace on 2014-12-17T14:55:24Z (GMT). No. of bitstreams: 1 AllanMM_capaatecap3.pdf: 1884008 bytes, checksum: e5ac07ccdc460d8abf9ed5ff7c0400de (MD5) Previous issue date: 2005-03-08 / In this work we present a new clustering method that groups up points of a data set in classes. The method is based in a algorithm to link auxiliary clusters that are obtained using traditional vector quantization techniques. It is described some approaches during the development of the work that are based in measures of distances or dissimilarities (divergence) between the auxiliary clusters. This new method uses only two a priori information, the number of auxiliary clusters Na and a threshold distance dt that will be used to decide about the linkage or not of the auxiliary clusters. The number os classes could be automatically found by the method, that do it based in the chosen threshold distance dt, or it is given as additional information to help in the choice of the correct threshold. Some analysis are made and the results are compared with traditional clustering methods. In this work different dissimilarities metrics are analyzed and a new one is proposed based on the concept of negentropy. Besides grouping points of a set in classes, it is proposed a method to statistical modeling the classes aiming to obtain a expression to the probability of a point to belong to one of the classes. Experiments with several values of Na e dt are made in tests sets and the results are analyzed aiming to study the robustness of the method and to consider heuristics to the choice of the correct threshold. During this work it is explored the aspects of information theory applied to the calculation of the divergences. It will be explored specifically the different measures of information and divergence using the R?nyi entropy. The results using the different metrics are compared and commented. The work also has appendix where are exposed real applications using the proposed method / Neste trabalho apresentamos um novo m?todo de clustering que agrupa pontos de um conjunto de dados em classes. O m?todo baseia-se em um algoritmo para liga??o de clusters auxiliares que s?o obtidos usando-se t?cnicas de quantiza??o vetorial tradicionais. S?o descritas algumas abordagens durante o desenvolvimento do trabalho que baseiam-se em medidas de dist?ncia ou dissimilaridade (diverg?ncia) entre os clusters auxiliares. Este novo m?todo utiliza apenas duas informa??es a priori, a saber: o n?mero de centros auxiliares Na e uma dist?ncia de limiar dt que ser? utilizada para decidir sobre a liga??o ou n?o dos clusters auxilares. O n?mero de clusters pode ser automaticamente encontrado pelo m?todo, que o faz com base na dist?ncia limiar dt escolhida. Analogamente, o n?mero de classes, pode ser fornecido como informa??o adicional para auxiliar na escolha do limiar correto. Algumas an?lises s?o feitas e os resultados s?o comparados com outros m?todos tradicionais de clustering. Neste trabalho s?o analisadas diferentes m?tricas de dissimilaridade e uma nova m?trica baseada no conceito de negentropia ? proposta. Al?m de agrupar pontos de um conjunto de classes, ? proposto um m?todo para o modelamento estat?stico das classes de modo a se obter uma express?o para a probabilidade de um ponto pertencer a uma das classes. Experimentos com diversos valores de Na e dt s?o realizados em conjuntos de teste e os resultados s?o analisados de maneira a se estudar a robustez do m?todo e propor heur?sticas para a escolha do limiar correto. No trabalho s?o explorados os aspectos de teoria da informa??o aplicados ao c?lculo das diverg?ncias. S?o exploradas em particular as diferen?as medidas de informa??o e diverg?ncia utilizando a entropia de R?nyi. Os resultados utilizando as diferentes m?tricas s?o comparados e comentados. O trabalho ainda conta com ap?ndices onde s?o expostas aplica??es reais utilizando o m?todo proposto

Page generated in 0.0691 seconds