pointDemo: Interactive Assessment Demo of Affinity Between Dot Clouds
In SyNet: Inference and Analysis of Sympatry Networks

Description Usage Details Value Note Author(s) See Also Examples

Using a graphical user interface (GUI), this function demonstrates the effects of changing the topology of dot clouds on the calculation of their strength of association.

1	pointDemo()

Two resources are used, a tcltk control window and a screen graphics device. In the first window, the user must specify the size of the dot clouds and can manipulate the layouts of point sets on the plotting area.

Once the "Draw!" button is pressed then the graphics device is waiting for the user to click and draw points. The length of the Euclidean minimum spanning trees (MST) for each set of points is indicated. The length of the MST associated to the joint set of points is also added. It is important to note how this last measure decreases as the dot clouds get close and interpenetrated. Sympatry is suggested when the joint MST is equal or lesser than the sum of individual MSTs (i.e. counter-synergic property).

This function was designed for illustrating the procedure oriented to measure the degree of association between dot clouds. Anyway, it prints a data frame into the R console specifying the coordinates for each plotted point.

It seems impossible to measure sympatry between geographical entities without enclosing records into areas. However, I think that the refinement of the idea underlying this game can liberate us from the Procrustean nature of thinking distributions as bounded areas.

Daniel A. Dos Santos <dadossantos@csnat.unt.edu.ar>

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