From b91a54d3baa771b97414202793cb5fd2d2dd20bb Mon Sep 17 00:00:00 2001
From: Alex Reisner <alex@alexreisner.com>
Date: Thu, 24 Mar 2011 13:20:36 -0400
Subject: [PATCH] Convert bearing to degrees CW from North.
---
lib/geocoder/calculations.rb | 4 ++-
test/geocoder_test.rb | 54 ++++++++++++++++++++++++++++--------
2 files changed, 46 insertions(+), 12 deletions(-)
diff --git a/lib/geocoder/calculations.rb b/lib/geocoder/calculations.rb
index 5a994406..77c47449 100644
--- a/lib/geocoder/calculations.rb
+++ b/lib/geocoder/calculations.rb
@@ -52,7 +52,9 @@ module Geocoder
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
+ # brng is in radians counterclockwise from due east.
+ # Convert to degrees clockwise from due north:
+ (90 - to_degrees(brng) + 360) % 360
end
##
diff --git a/test/geocoder_test.rb b/test/geocoder_test.rb
index 1b3f7b08..d0f53bbf 100644
--- a/test/geocoder_test.rb
+++ b/test/geocoder_test.rb
@@ -25,17 +25,6 @@ class GeocoderTest < Test::Unit::TestCase
assert (la_to_ny - 2444).abs < 10
end
- def test_compass_points
- 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
assert_equal [0.0, 0.5],
Geocoder::Calculations.geographic_center([[0,0], [0,1]])
@@ -183,6 +172,49 @@ class GeocoderTest < Test::Unit::TestCase
end
+ # --- bearing ---
+
+ def test_compass_points
+ 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_bearing_between
+ bearings = {
+ :n => 0,
+ :e => 90,
+ :s => 180,
+ :w => 270
+ }
+ points = {
+ :n => [41, -75],
+ :e => [40, -74],
+ :s => [39, -75],
+ :w => [40, -76]
+ }
+ directions = [:n, :e, :s, :w]
+ types = [:spherical]
+
+ types.each do |t|
+ directions.each_with_index do |d,i|
+ opp = directions[(i + 2) % 4] # opposite direction
+ p1 = points[d]
+ p2 = points[opp]
+
+ b = Geocoder::Calculations.bearing_between(*(p1 + p2))
+ assert (b - bearings[opp]).abs < 1,
+ "Bearing (#{t}) should be close to #{bearings[opp]} but was #{b}."
+ end
+ end
+ end
+
+
# --- Google ---
def test_google_result_components
--
GitLab