Module: Geocoder::Sql
Instance Method Summary collapse
-
#approx_bearing(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Totally lame bearing calculation.
-
#approx_distance(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Distance calculation for use with a database without trigonometric functions, like SQLite.
-
#full_bearing(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Fairly accurate bearing calculation.
-
#full_distance(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Distance calculation for use with a database that supports POWER(), SQRT(), PI(), and trigonometric functions SIN(), COS(), ASIN(), ATAN2(), DEGREES(), and RADIANS().
- #within_bounding_box(sw_lat, sw_lng, ne_lat, ne_lng, lat_attr, lon_attr) ⇒ Object
Instance Method Details
#approx_bearing(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Totally lame bearing calculation. Basically useless except that it returns something in databases without trig functions.
93 94 95 96 97 98 99 100 101 102 103 104 |
# File 'lib/geocoder/sql.rb', line 93 def approx_bearing(latitude, longitude, lat_attr, lon_attr, = {}) "CASE " + "WHEN (#{lat_attr} >= #{latitude.to_f} AND " + "#{lon_attr} >= #{longitude.to_f}) THEN 45.0 " + "WHEN (#{lat_attr} < #{latitude.to_f} AND " + "#{lon_attr} >= #{longitude.to_f}) THEN 135.0 " + "WHEN (#{lat_attr} < #{latitude.to_f} AND " + "#{lon_attr} < #{longitude.to_f}) THEN 225.0 " + "WHEN (#{lat_attr} >= #{latitude.to_f} AND " + "#{lon_attr} < #{longitude.to_f}) THEN 315.0 " + "END" end |
#approx_distance(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Distance calculation for use with a database without trigonometric functions, like SQLite. Approach is to find objects within a square rather than a circle, so results are very approximate (will include objects outside the given radius).
Distance and bearing calculations are *extremely inaccurate*. To be clear: this only exists to provide interface consistency. Results are not intended for use in production!
34 35 36 37 38 39 40 41 42 43 44 |
# File 'lib/geocoder/sql.rb', line 34 def approx_distance(latitude, longitude, lat_attr, lon_attr, = {}) units = [:units] || Geocoder.config.units dx = Geocoder::Calculations.longitude_degree_distance(30, units) dy = Geocoder::Calculations.latitude_degree_distance(units) # sin of 45 degrees = average x or y component of vector factor = Math.sin(Math::PI / 4) "(#{dy} * ABS(#{lat_attr} - #{latitude.to_f}) * #{factor}) + " + "(#{dx} * ABS(#{lon_attr} - #{longitude.to_f}) * #{factor})" end |
#full_bearing(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Fairly accurate bearing calculation. Takes a latitude, longitude, and an options hash which must include a :bearing value (:linear or :spherical).
Based on: www.beginningspatial.com/calculating_bearing_one_point_another
65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 |
# File 'lib/geocoder/sql.rb', line 65 def full_bearing(latitude, longitude, lat_attr, lon_attr, = {}) case [:bearing] || Geocoder.config.distances when :linear "CAST(" + "DEGREES(ATAN2( " + "RADIANS(#{lon_attr} - #{longitude.to_f}), " + "RADIANS(#{lat_attr} - #{latitude.to_f})" + ")) + 360 " + "AS decimal) % 360" when :spherical "CAST(" + "DEGREES(ATAN2( " + "SIN(RADIANS(#{lon_attr} - #{longitude.to_f})) * " + "COS(RADIANS(#{lat_attr})), (" + "COS(RADIANS(#{latitude.to_f})) * SIN(RADIANS(#{lat_attr}))" + ") - (" + "SIN(RADIANS(#{latitude.to_f})) * COS(RADIANS(#{lat_attr})) * " + "COS(RADIANS(#{lon_attr} - #{longitude.to_f}))" + ")" + ")) + 360 " + "AS decimal) % 360" end end |
#full_distance(latitude, longitude, lat_attr, lon_attr, options = {}) ⇒ Object
Distance calculation for use with a database that supports POWER(), SQRT(), PI(), and trigonometric functions SIN(), COS(), ASIN(), ATAN2(), DEGREES(), and RADIANS().
Based on the excellent tutorial at: www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL
13 14 15 16 17 18 19 20 21 22 |
# File 'lib/geocoder/sql.rb', line 13 def full_distance(latitude, longitude, lat_attr, lon_attr, = {}) units = [:units] || Geocoder.config.units earth = Geocoder::Calculations.earth_radius(units) "#{earth} * 2 * ASIN(SQRT(" + "POWER(SIN((#{latitude.to_f} - #{lat_attr}) * PI() / 180 / 2), 2) + " + "COS(#{latitude.to_f} * PI() / 180) * COS(#{lat_attr} * PI() / 180) * " + "POWER(SIN((#{longitude.to_f} - #{lon_attr}) * PI() / 180 / 2), 2)" + "))" end |
#within_bounding_box(sw_lat, sw_lng, ne_lat, ne_lng, lat_attr, lon_attr) ⇒ Object
46 47 48 49 50 51 52 53 54 55 |
# File 'lib/geocoder/sql.rb', line 46 def within_bounding_box(sw_lat, sw_lng, ne_lat, ne_lng, lat_attr, lon_attr) spans = "#{lat_attr} BETWEEN #{sw_lat} AND #{ne_lat} AND " # handle box that spans 180 longitude if sw_lng.to_f > ne_lng.to_f spans + "#{lon_attr} BETWEEN #{sw_lng} AND 180 OR " + "#{lon_attr} BETWEEN -180 AND #{ne_lng}" else spans + "#{lon_attr} BETWEEN #{sw_lng} AND #{ne_lng}" end end |