geodistance.rb

# Calculates geometric distances between all given points
# coordinates are passed as arguments, as in the following sample:
# ruby geodistance.rb 62.425,52.424 42.0,90.5256 0.0,0.0 90.0,-180.0
# returns the distance in kilometers

##
# Haversine Distance Calculation Function
#
# by https://gist.github.com/timols/5268103
# Accepts two coordinates in the form
# of a tuple. I.e.
#   geo_a  Array(Num, Num)
#   geo_b  Array(Num, Num)
#   miles  Boolean
#
# Returns the distance between these two
# points in either miles or kilometers

def haversine_distance(geo_a, geo_b, miles=false)
  # Get latitude and longitude
  lat1, lon1 = geo_a
  lat2, lon2 = geo_b
  
  # Calculate radial arcs for latitude and longitude
  dLat = (lat2 - lat1) * Math::PI / 180
  dLon = (lon2 - lon1) * Math::PI / 180
  
  
  a = Math.sin(dLat / 2) * 
  Math.sin(dLat / 2) +
  Math.cos(lat1 * Math::PI / 180) * 
  Math.cos(lat2 * Math::PI / 180) *
  Math.sin(dLon / 2) * Math.sin(dLon / 2)
  
  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a))
  
  d = 6371 * c * (miles ? 1 / 1.6 : 1)
end

raise "Must specify at least two points! (e.g. 62.425,52.424 42.0,90.5256" if ARGV.length < 2

points = []

i = 0
loop do
  lat, long = ARGV[i].split(",")
  lat = lat.to_f
  long = long.to_f
  raise "Coordinate ##{i+1} malformed" if (lat  < -90 or lat > 90  or long < -180 or long > 180)
  points.push([lat,long])
  i += 1
  break if i == ARGV.length
end

for i in 0..points.size do
  for j in i+1..points.size-1 do
    puts " #{points[i]} <-> #{points[j]} = #{haversine_distance(points[i], points[j])}" 
  end
end