From 0befaaf27e19b32e4a5bd703445a3ecd356fe61e Mon Sep 17 00:00:00 2001
From: Alex Reisner <alex@alexreisner.com>
Date: Tue, 3 Nov 2009 17:19:34 -0500
Subject: [PATCH] Fix a typo, clean up code, use full references to Math module
methods.
---
lib/geocoder.rb | 26 +++++++++++++-------------
test/geocoder_test.rb | 5 ++++-
2 files changed, 17 insertions(+), 14 deletions(-)
diff --git a/lib/geocoder.rb b/lib/geocoder.rb
index a68acff5..917a2ad2 100644
--- a/lib/geocoder.rb
+++ b/lib/geocoder.rb
@@ -215,28 +215,28 @@ module Geocoder
##
# Compute the geographic center (aka geographic midpoint, center of
- # gravity) for an array of [lat,lon] points.
+ # gravity) for an array of [lat,lon] points. Follows the procedure
+ # documented at http://www.geomidpoint.com/calculation.html.
#
def self.geographic_center(points)
# convert to Cartesian coordinates
- x = []; y = [], z = []
+ x = []; y = []; z = []
points.each do |p|
- x << cos(p[0]) * cos(p[1])
- y << cos(p[0]) * sin(p[1])
- z << sin(p[0])
+ x << Math.cos(p[0]) * Math.cos(p[1])
+ y << Math.cos(p[0]) * Math.sin(p[1])
+ z << Math.sin(p[0])
end
-
- # compute average coordinates
- avg = [x,y,z].map do |c|
- c.inject(0){ |tot,i| tot += i }
+
+ # compute average coordinate values
+ xa, ya, za = [x,y,z].map do |c|
+ c.inject(0){ |tot,i| tot += i } / c.size.to_f
end
# convert back to latitude/longitude
- xa, ya, za = avg
- lon = atan2(ya, xa)
- hyp = sqrt(xa * xa + ya * ya)
- lat = atan2(za, hyp)
+ lon = Math.atan2(ya, xa)
+ hyp = Math.sqrt(xa * xa + ya * ya)
+ lat = Math.atan2(za, hyp)
[lat,lon]
end
diff --git a/test/geocoder_test.rb b/test/geocoder_test.rb
index b7c18f47..ce19947d 100644
--- a/test/geocoder_test.rb
+++ b/test/geocoder_test.rb
@@ -15,6 +15,9 @@ class GeocoderTest < Test::Unit::TestCase
# sanity check
def test_geographic_center
- assert_equal 69, Geocoder.geographic_center([[0,0], [0,1]]).round
+ assert_equal [0.0, 0.5],
+ Geocoder.geographic_center([[0,0], [0,1]])
+ assert_equal [0.0, 1.0],
+ Geocoder.geographic_center([[0,0], [0,1], [0,2]])
end
end
--
GitLab