Hierarchical Agglomerative Clustering
Taking the community world map as a example
- HAC is a machine learning algorithm
 - The algorithm recursively merges the pair of clusters that minimally increases the linkage distance
 - The linkage distance is the average euclidean distance of the airport radian coordinates
 - More information about HAC on Wikipedia
 
Airports of the cluster center in the example
- Rzeszow Jasionka Airport, Poland
 - Cork Airport, Ireland
 - Halifax Stanfield International, Canada
 - Queen Beatrix International, Aruba
 - Kuwait International, Kuwait
 - Labuan Bajo Komodo Airport, Indonesia