Wind Pressure Coefficients Zoning Method Based on an Unsupervised Learning Algorithm

Table 1

Common clustering validity indices.

No.	Name	Formula	Optimal clustering number	References
1	CH index		Maximum value of the index	Caliński and Harabasz [22]
2	C Index		Minimum value of the index	Hubert and Levin [23]
3	Gamma index		Maximum value of the index	Baker and Hubert [24]
4	DB index		Minimum value of the index	Davies and Bouldin [25]
5	Hartigan index		Maximum difference between hierarchy levels of the index	Hartigan [26]
6	Tau index		Maximum value of the index
7	Scott index		Maximum difference between hierarchy levels of the index	Scott and Symons [27]
8	Marriot index		Maximum value of second differences between levels of the index	Marriot [28]
9	Friedman index		Maximum difference between hierarchy levels of the index	Friedman and Rubin [29]
10	Rubin index		Minimum value of second differences between levels of the index	Friedman and Rubin [29]
11	KL index		Maximum value of the index	Krzanowski and Lai [30]
12	Silhouette index	,	Maximum value of the index	Rousseeuw [31]
13	Dunn index		Maximum value of the index	Dunn [32]
14	SD index	σ = (VAR (V1), VAR (V2), …, VAR(VP)); Dmax = max(||ck − cz||) ∀k, z ∈ {1, 2, 3, …, q}; Dmin = min(||ck − cz||) ∀k, z ∈ {1, 2, 3, …, q}	Minimum value of the index	Halkidi et al. [33]