SimplifyRb is a Ruby port of simplify.js by Vladimir Agafonkin.

You can use this gem to reduce the number of points in a complex polyline / polygon, making use of an optimized Douglas-Peucker algorithm.

require 'simplify_rb'
points = [
  { x: 51.5256, y: -0.0875 },
  { x: 51.7823, y: -0.0912 }
]
tolerance = 1
high_quality = true
SimplifyRb::Simplifier.new.process(points, tolerance, high_quality)

points: An array of hashes, containing x,y coordinates.

tolerance: (optional, 1 by default): Affects the amount of simplification that occurs (the smaller, the less simplification).

high_quality: (optional, False by default): Flag to exclude the distance pre-processing. Produces higher quality results when true is passed, but runs slower.

You can also use custom points, such as a struct or object which responds to :x and :y, rather than hashes:

CustomPointStruct = Struct.new(:x, :y)
custom_points = [
  CustomPointStruct.new(51.5256, -0.0875),
  CustomPointStruct.new(51.7823, -0.0912)
]
tolerance = 1
high_quality = true
SimplifyRb::Simplifier.new.process(custom_points, tolerance, high_quality)

Add this line to your application's Gemfile:

gem 'simplify_rb'

And then execute:

$ bundle

Or install it yourself as:

$ gem install simplify_rb