2.5 Spatial movement analysis
In this analysis, we constructed networks of premises and abattoirs summarised by parish and then computed the Euclidean distance of the movements (Karney, 2013) based on parish centroids (1,032 polygons). Afterwards, we plotted the spatial movements on annual maps, representing the source and target by a vector between parish centroids and the direction of movement by an arrow, and added the frequency of movements by colours: <100 green, 101–500 blue and >500 red. From the network of premises, we summarise the total incoming and outgoing movements and calculate their balance to detect the most influential parishes, plotting the result on the map, looking for the areas with higher risk of disease spread.
Using network metrics and spatial movements, we plotted images and converted them into annual animations using six frames for every month, showing the monthly status of the centrality network metrics. The video sections contains A: representation of weighted origin/destiny movements on the map, vectors are plotted according with movement weights, parishes coloured by monthly In/Out/balance degree. B: Ingoing-outgoing mobilised pigs (parishes codes). C: percentage of accumulated active nodes. D: monthly movement weights. E: Active edges. Videos are available in the supporting information.