diff --git a/lib/geocoder/calculations.rb b/lib/geocoder/calculations.rb
index b99e35f0a6add04230c7ff5e0dbacfcd32ac42af..b617bad206abfacbd543ae825545830036ce070f 100644
--- a/lib/geocoder/calculations.rb
+++ b/lib/geocoder/calculations.rb
@@ -2,6 +2,14 @@ module Geocoder
module Calculations
extend self
+ ##
+ # Compass point names, listed clockwise starting at North.
+ #
+ # If you want bearings named using more, fewer, or different points
+ # override Geocoder::Calculations.COMPASS_POINTS with your own array.
+ #
+ COMPASS_POINTS = %w[N NE E SE S SW W NW]
+
##
# Calculate the distance between two points on Earth (Haversine formula).
# Takes two sets of coordinates and an options hash:
@@ -32,6 +40,29 @@ module Geocoder
c * conversions[options[:units]]
end
+ ##
+ # Calculate bearing between two sets of co-ordinates.
+ # Returns a number of degrees from due north (clockwise).
+ #
+ # Based on: http://www.movable-type.co.uk/scripts/latlong.html
+ #
+ def bearing_between(lat1, lon1, lat2, lon2)
+ dlon = to_radians((lon1 - lon2).abs)
+ y = Math.sin(dlon) * Math.cos(lat2)
+ x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) *
+ Math.cos(lat2) * Math.cos(dlon)
+ brng = Math.atan2(x,y)
+ (to_degrees(brng) + 360) % 360
+ end
+
+ ##
+ # Translate a bearing (float) into a compass direction (string, eg "North").
+ #
+ def compass_point(bearing, points = COMPASS_POINTS)
+ seg_size = 360 / points.size
+ points[((bearing + (seg_size / 2)) % 360) / seg_size]
+ end
+
##
# Compute the geographic center (aka geographic midpoint, center of
# gravity) for an array of geocoded objects and/or [lat,lon] arrays
@@ -88,35 +119,5 @@ module Geocoder
def km_in_mi
0.621371192
end
-
- ##
- # Calculate bearing between two sets of co-ordinates
- #
- def bearing_between(lat1, lon1, lat2, lon2, options = {})
- # Math courtesy of http://www.movable-type.co.uk/scripts/latlong.html
- dlon = to_radians((lon1 - lon2).abs)
-
- y = Math.sin(dlon) * Math.cos(lat2)
- x = Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) * Math.cos(lat2) * Math.cos(dlon)
- brng = Math.atan2(x,y)
- (to_degrees(brng) + 360) % 360
- end
-
- # If you want more or fewer points simply override Geocoder::Calculations.COMPASS_POINTS with your own array
- COMPASS_POINTS = [{:name => "North", :abbr => "N"},
- {:name => "North East", :abbr => "NE"},
- {:name => "East", :abbr => "E"},
- {:name => "South East", :abbr => "SE"},
- {:name => "South", :abbr => "S"},
- {:name => "South West", :abbr => "SW"},
- {:name => "West", :abbr => "W"},
- {:name => "North West", :abbr => "NW"}]
-
- ##
- # Compass direction (North, South, etc.) between two sets of co-ordinates
- def compass_point(bearing, points = COMPASS_POINTS)
- seg_size = 360/points.length
- points[((bearing + (seg_size/2) ) % 360) / seg_size]
- end
end
end
diff --git a/lib/geocoder/orms/active_record.rb b/lib/geocoder/orms/active_record.rb
index 0481f307cc5526f5854089fdef8c5c84517ff198..2633fb27e0a55d3f2eea41efc3581de010568385 100644
--- a/lib/geocoder/orms/active_record.rb
+++ b/lib/geocoder/orms/active_record.rb
@@ -59,7 +59,6 @@ module Geocoder::Orm
# +limit+ :: number of records to return (for LIMIT SQL clause)
# +offset+ :: number of records to skip (for OFFSET SQL clause)
# +select+ :: string with the SELECT SQL fragment (e.g. “id, nameâ€)
- # +bearing+ :: :line for straight line calcs, :sphere for spherical
#
def near_scope_options(latitude, longitude, radius = 20, options = {})
radius *= Geocoder::Calculations.km_in_mi if options[:units] == :km
@@ -77,30 +76,33 @@ module Geocoder::Orm
# Scope options hash for use with a database that supports POWER(),
# SQRT(), PI(), and trigonometric functions (SIN(), COS(), and ASIN()).
#
- # Taken from the excellent tutorial at:
+ # Distance calculations based on the excellent tutorial at:
# http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL
#
+ # Bearing calculation based on:
+ # http://www.beginningspatial.com/calculating_bearing_one_point_another
+ #
def full_near_scope_options(latitude, longitude, radius, options)
lat_attr = geocoder_options[:latitude]
lon_attr = geocoder_options[:longitude]
- bearing = case options[:bearing]
- # Credit for SQL query (adapted) http://www.beginningspatial.com/calculating_bearing_one_point_another
- when :line
- ", (DEGREES(ATAN2(( longitude - #{longitude} ), ( latitude - #{latitude} )))+360) % 360 AS bearing"
- when :spherical
- ", (DEGREES( ATAN2( SIN(RADIANS(longitude - #{longitude})) * COS(RADIANS(latitude)), ( COS(RADIANS(#{latitude})) * SIN(RADIANS(latitude)) ) - ( SIN(RADIANS(#{latitude})) * COS(RADIANS(latitude)) * COS(RADIANS(longitude - #{longitude})) ) )) + 360 ) % 360 AS bearing"
- else
- ""
- end
+ bearing = "(DEGREES(ATAN2( " +
+ "SIN(RADIANS(#{lon_attr} - #{longitude})) * " +
+ "COS(RADIANS(#{lat_attr})), (" +
+ "COS(RADIANS(#{latitude})) * " +
+ "SIN(RADIANS(#{lat_attr}))) - " +
+ "(SIN(RADIANS(#{latitude})) * " +
+ "COS(RADIANS(#{lat_attr})) * " +
+ "COS(RADIANS(#{lon_attr} - #{longitude}))))) + 360) % 360"
distance = "3956 * 2 * ASIN(SQRT(" +
"POWER(SIN((#{latitude} - #{lat_attr}) * " +
- "PI() / 180 / 2), 2) + COS(#{latitude} * PI()/180) * " +
+ "PI() / 180 / 2), 2) + COS(#{latitude} * PI() / 180) * " +
"COS(#{lat_attr} * PI() / 180) * " +
"POWER(SIN((#{longitude} - #{lon_attr}) * " +
"PI() / 180 / 2), 2) ))"
options[:order] ||= "#{distance} ASC"
default_near_scope_options(latitude, longitude, radius, options).merge(
- :select => "#{options[:select] || '*'}, #{distance} AS distance#{bearing}",
+ :select => "#{options[:select] || '*'}, " +
+ "#{distance} AS distance, #{bearing} AS bearing",
:having => "#{distance} <= #{radius}"
)
end
diff --git a/test/geocoder_test.rb b/test/geocoder_test.rb
index 458b59ee55683f13a7b6f325a4eefd9a2f857835..80c7255a3643bd0c54c9f1fb0c79b42a79f53d52 100644
--- a/test/geocoder_test.rb
+++ b/test/geocoder_test.rb
@@ -24,16 +24,14 @@ class GeocoderTest < Test::Unit::TestCase
end
def test_distance_between
- hash_north = {:name => "North", :abbr => "N"}
- hash_south = {:name => "South", :abbr => "S"}
- hash_nw = {:name => "North West", :abbr => "NW"}
- assert_equal hash_north, Geocoder::Calculations.compass_point(0)
- assert_equal hash_north, Geocoder::Calculations.compass_point(360)
- assert_equal hash_north, Geocoder::Calculations.compass_point(361)
- assert_equal hash_north, Geocoder::Calculations.compass_point(-22)
- assert_equal hash_nw, Geocoder::Calculations.compass_point(-23)
- assert_equal hash_south, Geocoder::Calculations.compass_point(180)
- assert_equal hash_south, Geocoder::Calculations.compass_point(181)
+ assert_equal "N", Geocoder::Calculations.compass_point(0)
+ assert_equal "N", Geocoder::Calculations.compass_point(1.0)
+ assert_equal "N", Geocoder::Calculations.compass_point(360)
+ assert_equal "N", Geocoder::Calculations.compass_point(361)
+ assert_equal "N", Geocoder::Calculations.compass_point(-22)
+ assert_equal "NW", Geocoder::Calculations.compass_point(-23)
+ assert_equal "S", Geocoder::Calculations.compass_point(180)
+ assert_equal "S", Geocoder::Calculations.compass_point(181)
end
def test_geographic_center_with_arrays