5 Concluding remarks
In this paper, we have mainly considered the multi-criteria ordered clustering problems. In order to deal with this type of problems, we have proposed an ordered clustering algorithm based on K-means clustering algorithm, which is called ordered K-means clustering algorithm. As the net outranking flow is an effective way to compute the sorting of all alternatives, we have applied the idea of net outranking flow to identify the clustering center of each cluster. Different from the classical k-means clustering algorithm, the sum of all alternatives’ net outranking flow can be used as the objective function. There is a complete ordered relationship between the clusters, which is obtained from the ordered K-means clustering algorithm.
The effectiveness of the ordered K-means clustering algorithm has been illustrated by the human development index problem. The ordered clustering results obtained from the ordered K-means clustering algorithm are very highly consistent with the HDI ranks. Meanwhile, the De Smet et al.’s method [21] has been introduced to compare with the ordered K-means clustering algorithm. The comparison analysis with the De Smet et al.’s method [21] has shown that (1) the ordered K-means clustering algorithm has a good robust; (2) the ordered K-means clustering algorithm can select the suitable cluster number according to the total sum of all alternatives’ net outranking flows; (3) the clustering results obtained from the ordered K-means clustering algorithm can take full account of the intra-relationships between alternatives.
For future work, we can consider the application of the proposed OKM to other practical problems related to ordered clustering. The deep discussions of using the nonlinear preference function in the OKM are interesting. In addition, the introduction of the proposed OKM to big data clustering is also meaningful.