Class: Overhelper

Inherits:
Object
  • Object
show all
Defined in:
lib/overhelper.rb

Constant Summary collapse

EARTH_RADIUS_IN_M = 
6371*1000

Class Method Summary collapse

Class Method Details

.convert_to_ways(json_string) ⇒ Object 



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# File 'lib/overhelper.rb', line 50

def self.convert_to_ways(json_string)
	data = JSON.parse(json_string)

	node_library = nodes_to_dict(data)

	ways = []
	for element in data["elements"]
		if element["type"] == "way"
			nodes_of_way = element["nodes"]
			prev_node = nil
			for node in nodes_of_way
				if prev_node != nil
					way = {}
					way[:lat1] = (node_library[prev_node])[:lat]
					way[:lon1] = (node_library[prev_node])[:lon]
					way[:lat2] = (node_library[node])[:lat]
					way[:lon2] = (node_library[node])[:lon]
					ways << way
				end
				prev_node = node
			end
		end
	end

	return ways
end

.distance_in_m(lat1, lon1, lat2, lon2) ⇒ Object 



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# File 'lib/overhelper.rb', line 14

def self.distance_in_m(lat1, lon1, lat2, lon2)
=begin
* Computes distance between two points on Earth using Haversine formula
* Earth is assumed to be sphere, errors from assuming spherical geometry might be up to 0.55% crossing the equator
* source: https://en.wikipedia.org/wiki/Haversine_formula and http://www.movable-type.co.uk/scripts/latlong.html
=end
	lat1 = lat1 * Math::PI / 180
	lon1 = lon1 * Math::PI / 180
	lat2 = lat2 * Math::PI / 180
	lon2 = lon2 * Math::PI / 180

	dLat = (lat2 - lat1).abs;
	dLon = (lon2 - lon1).abs;

	#a: square of half the chord length between the points
	a = Math.sin(dLat / 2) * Math.sin(dLat / 2);
	a += Math.sin(dLon / 2) * Math.sin(dLon / 2) * Math.cos(lat2) * Math.cos(lat1);
	angularDistanceInRadians = Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
	delta_in_m = 2 * EARTH_RADIUS_IN_M * angularDistanceInRadians;
	return delta_in_m
end

.list_of_locations_from_overpass_into_array(list, data = []) ⇒ Object 



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# File 'lib/overhelper.rb', line 3

def self.list_of_locations_from_overpass_into_array(list, data=[])
  list.split(/[\n]+/m).each{|element|
      element = Hash[[:lat, :lon].zip(element.split(/[\s]+/m))]
      element[:lat] = element[:lat].to_f
      element[:lon] = element[:lon].to_f
      data << element
  }
  return data
end

.nodes_to_dict(data) ⇒ Object 



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# File 'lib/overhelper.rb', line 37

def self.nodes_to_dict(data)
	node_library = {}
	for element in data["elements"]
		if element["type"] == "node"
			saved = {}
			saved[:lat] = element["lat"].to_f
			saved[:lon] = element["lon"].to_f
			node_library[element["id"]] = saved
		end
	end
	return node_library
end