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TESI DOCTORAL - La Salle

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B.1. Clustering indeterminacies in unimodal data sets<br />

clustering count<br />

Segmentation Baseline<br />

40<br />

30<br />

20<br />

10<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(a) Baseline<br />

clustering count<br />

40<br />

30<br />

20<br />

10<br />

Segmentation PCA<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(b) PCA<br />

clustering count<br />

40<br />

30<br />

20<br />

10<br />

Segmentation ICA<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(c) ICA<br />

clustering count<br />

40<br />

30<br />

20<br />

10<br />

Segmentation RP<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(d) RP<br />

Figure B.10: Histograms of the φ (NMI) values obtained on each data representation in the<br />

Segmentation data set.<br />

clustering count<br />

60<br />

40<br />

20<br />

BBC Baseline<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(a) Baseline<br />

clustering count<br />

60<br />

40<br />

20<br />

BBC PCA<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(b) PCA<br />

clustering count<br />

60<br />

40<br />

20<br />

BBC ICA<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(c) ICA<br />

clustering count<br />

60<br />

40<br />

20<br />

BBC NMF<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(d) NMF<br />

clustering count<br />

60<br />

40<br />

20<br />

BBC RP<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(e) RP<br />

Figure B.11: Histograms of the φ (NMI) values obtained on each data representation in the<br />

BBC data set.<br />

B.1.12 PenDigits data set<br />

In this case, the distinct object representations present a reasonably similar behaviour<br />

according to the histograms depicted in figure B.12. Assuming a simplifying viewpoint,<br />

these can be decomposed into a negatively skewed peak with its acme around φ (NMI) =0.6,<br />

and two other narrow peaks, one located near φ (NMI) =0.8 and the other on the low range<br />

of the histogram. Thus, as opposed to what has been observed in other data collections, the<br />

application of the twenty-eight clustering algorithms on the distinct object representations<br />

yield comparable quality results in this data set.<br />

clustering count<br />

30<br />

20<br />

10<br />

PenDigits Baseline<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(a) Baseline<br />

clustering count<br />

30<br />

20<br />

10<br />

PenDigits PCA<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(b) PCA<br />

clustering count<br />

30<br />

20<br />

10<br />

PenDigits ICA<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(c) ICA<br />

clustering count<br />

30<br />

20<br />

10<br />

PenDigits NMF<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(d) NMF<br />

clustering count<br />

30<br />

20<br />

10<br />

PenDigits RP<br />

0<br />

0 0.5 1<br />

φ (NMI)<br />

(e) RP<br />

Figure B.12: Histograms of the φ (NMI) values obtained on each data representation in the<br />

PenDigits data set.<br />

240

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