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TESI DOCTORAL - La Salle

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4.3. Selection-based self-refining<br />

φ (NMI)<br />

1<br />

0.5<br />

0<br />

E<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

φ (NMI)<br />

HGPA<br />

1<br />

0.5<br />

0<br />

(c) HGPA<br />

φ (NMI)<br />

1<br />

0.5<br />

0<br />

E<br />

E<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

λ c 15<br />

λ c 15<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

CSPA<br />

(a) CSPA<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

φ (NMI)<br />

KMSAD<br />

1<br />

0.5<br />

0<br />

E<br />

(f) KMSAD<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

λ c 15<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

φ (NMI)<br />

MCLA<br />

1<br />

0.5<br />

0<br />

(d) MCLA<br />

φ (NMI)<br />

1<br />

0.5<br />

0<br />

E<br />

E<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

λ c 15<br />

λ c 15<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

EAC<br />

(b) EAC<br />

φ (NMI)<br />

SLSAD<br />

1<br />

0.5<br />

0<br />

E<br />

(g) SLSAD<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

λref<br />

λ c 2<br />

λ c 5<br />

λ c 10<br />

λ c 15<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

ALSAD<br />

(e) ALSAD<br />

λ c 15<br />

λ c 20<br />

λ c 30<br />

λ c 40<br />

λ c 50<br />

λ c 60<br />

λ c 75<br />

λ c 90<br />

Figure 4.3: φ (NMI) boxplots of the cluster ensemble E, the selected cluster ensemble component<br />

λref and the self-refined consensus clustering solutions λc p i on the Zoo data collection<br />

across all the consensus functions employed. The green dashed vertical line identifies the<br />

clustering solution selected by the supraconsensus function in each experiment.<br />

ing sections present a separate study of the results yielded by the self-refining procedure<br />

itself and the supraconsensus function that, a posteriori, must select the best self-refining<br />

consensus clustering solution.<br />

4.3.1 Evaluation of the selection-based self-refining process<br />

As far as the evaluation of the selection-based consensus self-refining procedure is concerned,<br />

four analysis have been conducted. For starters, we have measured the percentage<br />

of experiments in which the procedure of self-refining yields a better quality clustering<br />

than the cluster ensemble component selected as a reference (i.e. the one maximizing its<br />

φ (ANMI) with respect to the cluster ensemble E, referred to as λref). The results, averaged<br />

across all the unimodal data collections employed in this work, are presented in table 4.12<br />

as a function of the consensus function employed. In average, the self-refining procedure,<br />

when conducted on select cluster ensembles created upon the selection of λref, yields better<br />

clustering solutions in a 56% of the conducted experiments.<br />

This figure is notably lower than what was obtained when the select cluster ensemble<br />

124

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