help define cutting levels. Let us plot the fusion level values for some of the
dendrograms produced above (Fig. 4.8).
nrow(spe):2,
col = "red",
cex = 0.8)
# Plot the fusion level values of the UPGMA clustering
plot(
spe.ch.UPGMA$height,
nrow(spe):2,
type = "S",
main = "Fusion levels - Chord - UPGMA",
ylab = "k (number of clusters)",
xlab = "h (node height)",
col = "grey"
)
par(mfrow = c(2, 2))
# Plot the fusion level values of the complete linkage clustering
plot(
spe.ch.complete$height,
nrow(spe):2,
type = "S",
main = "Fusion levels - Chord - Complete",
ylab = "k (number of clusters)",
xlab = "h (node height)",
col = "grey"
)
text(spe.ch.complete$height,
nrow(spe):2,
0.2
0.4
0.6
0.8
1.0
1.2
1.4
5 10 15 20 25
30
Fusion levels - Chord - Complete
h (node height)
k (number of clusters)
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
0.2
0.4
0.6
0.8
1.0
1.2
5 10 15
20 25
30
Fusion levels - Chord - UPGMA
h (node height)
k (number of clusters)
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
0.5
1.0
1.5
2.0
2.5
3.0
3.5
5 10 15 20 25 30
Fusion levels - Chord - Ward
h (node height)
k (number of clusters)
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
0.5
1.0
1.5
2.0
2.5
3.0
5 10 15
20 25 30
Fusion levels - Chord - Beta-flexible
h (node height)
k (number of clusters)
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
Fig. 4.8 Graphs of the fusion level values of four dendrograms. When read from right to left, long
horizontal lines preceding steep increases suggest cutting levels, e.g. the 9-group solution in the
complete linkage dendrogram or the 4-group solution in the Ward dendrogram
4.7 Interpreting and Comparing Hierarchical Clustering Results
75