Module: Geokit::Mappable::ClassMethods

Defined in:
lib/geokit/mappable.rb

Overview

:nodoc:

Instance Method Summary collapse

Instance Method Details

#distance_between(from, to, options = {}) ⇒ Object

Returns the distance between two points. The from and to parameters are required to have lat and lng attributes. Valid options are: :units - valid values are :miles, :kms, :nms (Geokit::default_units is the default) :formula - valid values are :flat or :sphere (Geokit::default_formula is the default)



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# File 'lib/geokit/mappable.rb', line 36

def distance_between(from, to, options={})
  from=Geokit::LatLng.normalize(from)
  to=Geokit::LatLng.normalize(to)
  return 0.0 if from == to # fixes a "zero-distance" bug
  units = options[:units] || Geokit::default_units
  formula = options[:formula] || Geokit::default_formula
  case formula
  when :sphere then distance_between_sphere(from, to, units)
  when :flat   then distance_between_flat(from, to, units)
  end
end

#distance_between_flat(from, to, units) ⇒ Object 



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# File 'lib/geokit/mappable.rb', line 57

def distance_between_flat(from, to, units)
  lat_length = units_per_latitude_degree(units) * (from.lat - to.lat)
  lng_length = units_per_longitude_degree(from.lat, units) * (from.lng - to.lng)
  Math.sqrt(lat_length ** 2 + lng_length ** 2)
end

#distance_between_sphere(from, to, units) ⇒ Object 



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# File 'lib/geokit/mappable.rb', line 48

def distance_between_sphere(from, to, units)
  lat_sin = Math.sin(deg2rad(from.lat)) * Math.sin(deg2rad(to.lat))
  lat_cos = Math.cos(deg2rad(from.lat)) * Math.cos(deg2rad(to.lat))
  lng_cos = Math.cos(deg2rad(to.lng) - deg2rad(from.lng))
  units_sphere_multiplier(units) * Math.acos(lat_sin + lat_cos * lng_cos)
rescue *math_error_classes
  0.0
end

#endpoint(start, heading, distance, options = {}) ⇒ Object

Given a start point, distance, and heading (in degrees), provides an endpoint. Returns a LatLng instance. Typically, the instance method will be used instead of this method.



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# File 'lib/geokit/mappable.rb', line 89

def endpoint(start,heading, distance, options={})
  units   = options[:units] || Geokit::default_units
  ratio   = distance.to_f / units_sphere_multiplier(units)
  start   = Geokit::LatLng.normalize(start)
  lat     = deg2rad(start.lat)
  lng     = deg2rad(start.lng)
  heading = deg2rad(heading)

  sin_ratio = Math.sin(ratio)
  cos_ratio = Math.cos(ratio)
  sin_lat = Math.sin(lat)
  cos_lat = Math.cos(lat)

  end_lat = Math.asin(sin_lat * cos_ratio +
                      cos_lat * sin_ratio * Math.cos(heading))

  end_lng = lng + Math.atan2(Math.sin(heading) * sin_ratio * cos_lat,
                             cos_ratio - sin_lat * Math.sin(end_lat))

  LatLng.new(rad2deg(end_lat),rad2deg(end_lng))
end

#geocode(location, options = {}) ⇒ Object

Geocodes a location using the multi geocoder.

Raises:



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# File 'lib/geokit/mappable.rb', line 126

def geocode(location, options = {})
  res = Geocoders::MultiGeocoder.geocode(location, options)
  return res if res.success?
  raise Geokit::Geocoders::GeocodeError
end

#heading_between(from, to) ⇒ Object

Returns heading in degrees (0 is north, 90 is east, 180 is south, etc) from the first point to the second point. Typicaly, the instance methods will be used instead of this method.



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# File 'lib/geokit/mappable.rb', line 74

def heading_between(from,to)
  from=Geokit::LatLng.normalize(from)
  to=Geokit::LatLng.normalize(to)

  d_lng=deg2rad(to.lng-from.lng)
  from_lat=deg2rad(from.lat)
  to_lat=deg2rad(to.lat)
  y=Math.sin(d_lng) * Math.cos(to_lat)
  x=Math.cos(from_lat)*Math.sin(to_lat)-Math.sin(from_lat)*Math.cos(to_lat)*Math.cos(d_lng)
  heading=to_heading(Math.atan2(y,x))
end

#math_error_classes ⇒ Object 



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# File 'lib/geokit/mappable.rb', line 63

def math_error_classes
  error_classes = [Errno::EDOM]

  # Ruby 1.9 raises {Math::DomainError}, but it is not defined in Ruby
  # 1.8. Backwards-compatibly rescue both errors.
  error_classes << Math::DomainError if defined?(Math::DomainError)
end

#midpoint_between(from, to, options = {}) ⇒ Object

Returns the midpoint, given two points. Returns a LatLng. Typically, the instance method will be used instead of this method. Valid option:

:units - valid values are :miles, :kms, or :nms (:miles is the default)



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# File 'lib/geokit/mappable.rb', line 115

def midpoint_between(from,to,options={})
  from=Geokit::LatLng.normalize(from)

  units = options[:units] || Geokit::default_units

  heading=from.heading_to(to)
  distance=from.distance_to(to,options)
  midpoint=from.endpoint(heading,distance/2,options)
end