Figure 3From: Spatiotemporal distributions of population in Seoul: joint influence of ridership and accessibility of the subway systemDendrograms of hierarchical agglomerative clustering. The dendrograms illustrate how clusters are composed according to the (a) single, (b) average, and (c) complete linkage criteria. At the start of the dendrogram, each time window is labelled with t (\(= 0,1,\ldots , 23\) in 24-hour notation). From bottom to top, time windows with high correlations are preferentially merged, as depicted by the inverted U-shaped link with the height representing the dissimilarity under each criterion with Eq. (1). Following the dendrograms, one can find the clusters commonly observed in all three criteria. Those with the least dissimilarity are the time windows from \(t=0\) to 5 (blue links) and from \(t=9\) to 17 (red links). At this level of dissimilarity in the complete criterion, a cluster including \(t=19\) and 20 (green links) is additionally observedBack to article page