Distance

Provides a set of distance functions for use in GIS or graphic applications.

Installation

defp deps do
  [{:distance, "~> 0.2.1"}]
end

Functions

Point-Point Distance

Calculate geometric distance between two or more points (two- or three-dimensional):

Distance.distance({2, -1}, {-1, 3}) # => 5
Distance.distance({2, -1, 4}, {-1, 3, 2}) # => 5.385...

Distance.distance([{2.5, 2.5}, {4, 0.8}, {2.5, 3.1}, {2.5, 3.1}]) # => 5.013...

Calculate the square of the geometric distance between two points (useful as a faster way to compare distances between points without the need for an expensive square root operation):

Distance.distance_squared({2, -1}, {-1, 3}) # => 25
Distance.distance_squared({2, -1, 4}, {-1, 3, 2}) # => 29

Point-Segment Distance

Calculate geometric distance between a point and the closest point on a line segment. For instance the distance between the point (3, 3) and the line segment between (-2, 1) and (5, 3).

Distance.segment_distance({3, 2}, {-2, 1}, {5, 3}) # => 0.412...

Similar to the distance function, there is a squared version for faster calculations when needed:

Distance.segment_distance_squared({3, 2}, {-2, 1}, {5, 3}) # => 0.170...

Great Circle Distance

Calculate great circle distances (shortest travel distance on the surface of a spherical Earth) given a two longitude-latitude pairs. This is an implementation of the Haversine formula and approximates using a spherical (non-ellipsoid) Earth with a mean radius of 6,371,008.8 meters derived from the WGS84 datum.

The function accepts two tuples in the form of {longitude, latitude} and returns the distance in meters. It will also accept a List of tuples.

Distance.GreatCircle.distance({-96.796667, 32.775833}, {126.967583, 37.566776}) # => 10974882.74...

Distance.GreatCircle.distance([
  {-96.796667, 32.775833},
  {126.967583, 37.566776},
  {151.215158, -33.857406},
  {55.274180, 25.197229},
  {6.942661, 50.334057},
  {-97.635926, 30.134442}
]) # => 44728827.849...