geo-yoots

Functions for working with location objects on Earth.

Features

Distance Functions

Supported objects

1. Point to point distance
2. Point to polyline distance
3. Point to circle distance
4. Point to polygon distance

Points are (latitude, longitude) pairs. All units are kilometers.

user=> (require '[geo-yoots.sphere.distance.core :as geo.sphere.dist])
nil

user=> (def pts
  #_=>   (list
  #_=>     [-12.338184 -177.614518]
  #_=>     [-11.851550 -178.516962]
  #_=>     [-13.764120 -178.513183]
  #_=>     [-11.670954 -175.592518]
  #_=>     [-11.188348  178.891297]
  #_=>     [-14.929683  179.326528]))
#'user/pts

user=> (def polyline
  #_=>   [[-15.290669  179.159774]
  #_=>    [-11.469978  179.626362]
  #_=>    [ -9.559677 -177.255858]])
#'user/polyline

user=> (def polygon-1
  #_=>   [[-15.290669  179.159774]
  #_=>    [-11.469978  179.626362]
  #_=>    [ -9.559677 -177.255858]
  #_=>    [-13.678565 -174.857297]
  #_=>    [-17.228967 -177.598549]
  #_=>    [-13.836214 -177.062038]
  #_=>    [-12.340054 -178.316774]])
#'user/polygon-1

user=> (def polygon-2
  #_=>   [[ 1.000000  0.000000]
  #_=>    [ 0.000000  1.000000]
  #_=>    [-1.000000  0.000000]
  #_=>    [ 0.000000 -1.000000]])
#'user/polygon-2

Point to point

user=> (geo.sphere.dist/to-point (nth pts 0) (nth pts 1))
112.08264672107683

Point to polyline

user=> (geo.sphere.dist/to-polyline (nth pts 0) polyline)
240.6904983870271

Point to cirlce

(geo.sphere.distance/to-circle pt center radius)

Point to polygon

polygon-1 above

user=> (require '[geo-yoots.sphere.distance.signed :as geo.sphere.sdist])
nil

user=> (clojure.pprint/pprint (map #(geo.sphere.sdist/to-polygon % polygon-1) pts))
(-59.28097835060063
 -58.534169474670456
 84.17469003085837
 42.01298834918836
 86.06814827087875
 -12.089077457271761)
nil

Distance Boolean Functions

Polyline, circle and polygon structures support distance predicates - i.e. Are input points within distance to geometry.

(def limit 1.75) ;; kilometers
(geo.sphere.dist/within-distance-to-polyline? limit pt polyline)

Inclusion Tests

Point in polygon

Convex and Non-Convex Simple Polygons

(geo.sphere.inclusion/point-in-polygon? pt polygon)

Area Functions

Calculate polygon areas using the sphere.area package.

polygon-1 above

user=> (require '[geo-yoots.sphere.area.core :as geo.sphere.area])
nil

user=> (geo.sphere.area/polygon polygon-1)
221875.26084778266

user=> (geo.sphere.area/polygon polygon-2)
24740.08632334546

Implementation

Distance Functions

• https://en.wikipedia.org/wiki/Spherical_trigonometry
• https://mathworld.wolfram.com/SphericalCoordinates.html

Area Functions

• https://en.wikipedia.org/wiki/Shoelace_formula
• https://en.wikipedia.org/wiki/Rotation_matrix

License

Copyright © 2020 Navil Charles

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.