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Wyświetlanie 1-3 z 3
Tytuł:
Using the one-versus-rest strategy with samples balancing to improve pairwise coupling classification
Autorzy:
Chmielnicki, W.
Stąpor, K.
Powiązania:
https://bibliotekanauki.pl/articles/330749.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
multiclass classification
pairwise coupling
problem decomposition
support vector machine (SVM)
klasyfikacja wieloklasowa
rozkład problemu
maszyna wektorów wspierających
Opis:
The simplest classification task is to divide a set of objects into two classes, but most of the problems we find in real life applications are multi-class. There are many methods of decomposing such a task into a set of smaller classification problems involving two classes only. Among the methods, pairwise coupling proposed by Hastie and Tibshirani (1998) is one of the best known. Its principle is to separate each pair of classes ignoring the remaining ones. Then all objects are tested against these classifiers and a voting scheme is applied using pairwise class probability estimates in a joint probability estimate for all classes. A closer look at the pairwise strategy shows the problem which impacts the final result. Each binary classifier votes for each object even if it does not belong to one of the two classes which it is trained on. This problem is addressed in our strategy. We propose to use additional classifiers to select the objects which will be considered by the pairwise classifiers. A similar solution was proposed by Moreira and Mayoraz (1998), but they use classifiers which are biased according to imbalance in the number of samples representing classes.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 1; 191-201
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Efficient decision trees for multi-class support vector machines using entropy and generalization error estimation
Autorzy:
Kantavat, P.
Kijsirikul, B.
Songsiri, P.
Fukui, K. I.
Numao, M.
Powiązania:
https://bibliotekanauki.pl/articles/330532.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
support vector machine
multi-class classification
generalization error
decision tree
maszyna wektorów wsparcia
klasyfikacja wieloklasowa
błąd generalizacji
drzewo decyzyjne
Opis:
We propose new methods for support vector machines using a tree architecture for multi-class classification. In each node of the tree, we select an appropriate binary classifier, using entropy and generalization error estimation, then group the examples into positive and negative classes based on the selected classifier, and train a new classifier for use in the classification phase. The proposed methods can work in time complexity between O(log2 N) and O(N), where N is the number of classes. We compare the performance of our methods with traditional techniques on the UCI machine learning repository using 10-fold cross-validation. The experimental results show that the methods are very useful for problems that need fast classification time or those with a large number of classes, since the proposed methods run much faster than the traditional techniques but still provide comparable accuracy.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2018, 28, 4; 705-717
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability of gene selection methods for multiclass clssification
Autorzy:
Student, S.
Fujarewicz, K.
Powiązania:
https://bibliotekanauki.pl/articles/333948.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Śląski. Wydział Informatyki i Nauki o Materiałach. Instytut Informatyki. Zakład Systemów Komputerowych
Tematy:
selekcja genów
metoda cząstkowych najmniejszych kwadratów
klasyfikacja wieloklasowa
gene selection
partial least squares
stability selection
bootstrap .632+
multiclass classification
BBFR
Opis:
A big problem in applying DNA microarrays for classification is dimension of the dataset. Recently we proposed a gene selection method based on Partial Least Squares (PLS) for searching best genes for classification. The new idea is to use PLS not only as multiclass approach, but to construct more binary selections that use one versus rest and one versus one approaches. Ranked gene lists are highly instable in the sense, that a small change of the data set often leads to big change of the obtained ordered list. In this article, we take a look at the assessment of stability of our approaches. We compare the variability of the obtained ordered lists from proposed methods with well known Recursive Feature Elimination (RFE) method and classical t-test method. This paper focuses on effective identification of informative genes. As a result, a new strategy to find small subset of significant genes is designed. Our results on real cancer data show that our approach has very high accuracy rate for different combinations of classification methods giving in the same time very stable feature rankings.
Źródło:
Journal of Medical Informatics & Technologies; 2010, 15; 101-107
1642-6037
Pojawia się w:
Journal of Medical Informatics & Technologies
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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