Fig. 2
From: Quantifying the spatial spillover effects of non-pharmaceutical interventions on pandemic risk
Geographical representation of class map and spatial weight matrix.A The class map by Kmeans method according to the intrastate human mobility. Note: US states are divided into four groups: (1) Region 1 (\(r_1\)): 22 regions with relatively low human mobility; (2) Region 2 (\(r_2\)): 18 regions with intermediate human mobility; (3) Region 3 (\(r_3\)): 6 regions with higher human mobility; (4) Region 4 (\(r_4\)): 3 regions with the highest human mobility. B Flow matrix with nearest 8 neighbors: \(49 \times 49\) interstate interaction matrix, where each region is only connected to its closest 8 neighbors. The purple line represents neighbors of California. The color indicates the size of the element of the spatial weights. The darker the color, the larger the weight value