Efficient Clustering for Orders - Mining Complex Data - page 261

Table 15.3. The top 10 ranked up and the worst 10 ranked down sushi

Cluster 1 Cluster 2

# 2313 2687

1 egg ♣ +74 ark shell ♥ +63

♣ ♠

2 cucumber roll +62 crab liver +39

♣ ♥

3 fermented bean roll +38 turban shell +26

4 octopus +36 sea bass +23

5 deep-fried tofu ♣ +33 abalone ♥ +22

6 salad ♣ +29 tsubu shell +16

7 pickled plum & perilla leaf roll ♣ +28 angler liver ♠ +16

8 fermented bean ♣ +26 sea urchin ♠ +15

9 perilla leaf roll ♣ +24 clam ♥ +13

10 raw beef +21 hardtail ♦ +13

. .

91 flying fish ♦ -10 chili cod roe roll ♣ -15

92 young yellowtail ♦ -12 pickled plum roll ♣ -15

93 battera ♦ -13 shrimp -17

94 sea bass -14 tuna roll ♣ -19

95 amberjack ♦ -37 egg ♣ -19

96 hardtail ♦ -41 salad roll ♣ -27

97 fluke fin -46 deep-fried tofu ♣ -30

98 abalone ♥ -63 salad ♣ -32

-84 octopus -57
100 salmon roe -85 squid -82
NOTE: Sushi in each cluster derived by k -o'means-EBC were sorted in descending order of
rankup( x j ) (Equation (15.18)). In top row labeled “#”, the sizes of clusters were listed. The
upper half of the tables show the ranked up sushi, and the bottom half show the ranked down
sushi. Just to the right of each sushi name, the rankup( x j ) values are shown.

99 sea urchin ♠

was derived. We say that x j is ranked up if rankup( x j ) is positive, and that it is ranked
down if rankup( x j ) is negative. If the object x j was ranked up, it was ranked higher in
cluster center O k than in the entire center O ∗ . By observing the sushi whose the absolute
values of rankup( x j ) were large, we investigated the characteristics of each cluster.
Table 15.3 list the most 10 ranked up and the most 10 ranked down sushi in clusters
derived by k -o'means-EBC. That is to say, we show the objects whose rankup( x j )
were the 1st to 10th largest, and were the 1st to 10th smallest. The upper half of the
tables shows the ranked up sushi, and the bottom half shows the ranked down sushi. In
the top row labeled “#”, the sizes of the clusters are listed. Sushi names that we were
not able to translate into English were written using their original Japanese names in
italics . Just to the right of each sushi name, the rankup( x j ) values are shown.
We interpreted this table qualitatively. In this table, the mark indicates objects

whose internal organs, such as liver or sweetbread, are eaten. The sushi marked by

♠

♦

are so-called blue fish , and those marked by are clams or shells. These sushi were

rather substantial and oily, as revealed in the A1 row of Table 15.2. However, we could
not conclude that the respondents in cluster 2 preferred simply oily sushi. For example,

♥