Feature request: `gis:min-distance-of` primitive to compute minimum distance between GeoFeatures

[EwoutH]

Summary

Add a gis:min-distance-of reporter that returns the minimum geometric distance between a target geometry (a VectorFeature or NetLogo agent with a GIS geometry) and any member of a collection (a VectorDataset or an agentset). Distance follows the units of the active GIS projection (e.g., meters if projected, degrees if unprojected lat/lon). Returns 0 when geometries touch or intersect.

This feature request builds on the work started in PR #46, and #17, #18 and #19, originally written by @josephzhao.

Proposed API

gis:min-distance-of <collection> <target>  ;; -> number

Parameters

• <collection>: VectorDataset | agentset
• <target>: VectorFeature | agent (turtle/link/patch) that has a GIS geometry

Return value

• Minimum JTS geometry distance between <target> and any geometry in <collection>.

Example usage

extensions [ gis ]

to setup
  ca
  set roads-ds gis:load-dataset "roads.shp"
  ; ensure appropriate projection/transform is set for meaningful units
end

to-report dist-to-roads [car]
  report gis:min-distance-of roads-ds car
end

to-report nearest-obstacle-dist [peds]
  ; peds is an agentset of pedestrian turtles
  let d gis:min-distance-of peds one-of cars
  report d
end