How to calculate the distance between two GPS coordinates without using Google Maps API?

Question

I\'m wondering if there\'s a way to calculate the distance of two GPS coordinates without relying on Google Maps API.

My app may receive the coordinates in float or

Answer 1

Distance between two coordinates on earth is usually calculated using Haversine formula. This formula takes into consideration earth shape and radius. This is the code I use to calculate distance in meters.

def distance(loc1, loc2)
  rad_per_deg = Math::PI/180  # PI / 180
  rkm = 6371                  # Earth radius in kilometers
  rm = rkm * 1000             # Radius in meters

  dlat_rad = (loc2[0]-loc1[0]) * rad_per_deg  # Delta, converted to rad
  dlon_rad = (loc2[1]-loc1[1]) * rad_per_deg

  lat1_rad, lon1_rad = loc1.map {|i| i * rad_per_deg }
  lat2_rad, lon2_rad = loc2.map {|i| i * rad_per_deg }

  a = Math.sin(dlat_rad/2)**2 + Math.cos(lat1_rad) * Math.cos(lat2_rad) * Math.sin(dlon_rad/2)**2
  c = 2 * Math::atan2(Math::sqrt(a), Math::sqrt(1-a))

  rm * c # Delta in meters
end

puts distance([46.3625, 15.114444],[46.055556, 14.508333])
# => 57794.35510874037

Answer 2

Look at gem Geocoder(railscast)

If you store your coordinates in db, it calculate distance using database. But works good in other cases too.

Answer 3

Converted the accepted answer to Swift 3.1 (works on Xcode 8.3), in case anyone needs it:

public static func calculateDistanceMeters(departure: CLLocationCoordinate2D, arrival: CLLocationCoordinate2D) -> Double {

    let rad_per_deg = Double.pi / 180.0 // PI / 180
    let rkm = 6371.0                    // Earth radius in kilometers
    let rm = rkm * 1000.0               // Radius in meters

    let dlat_rad = (arrival.latitude - departure.latitude) * rad_per_deg // Delta, converted to rad
    let dlon_rad = (arrival.longitude - departure.longitude) * rad_per_deg

    let lat1_rad = departure.latitude * rad_per_deg
    let lat2_rad = arrival.latitude * rad_per_deg

    let sinDlat = sin(dlat_rad/2)
    let sinDlon = sin(dlon_rad/2)
    let a = sinDlat * sinDlat + cos(lat1_rad) * cos(lat2_rad) * sinDlon * sinDlon
    let c = 2.0 * atan2(sqrt(a), sqrt(1-a))

    return rm * c
}

Answer 4

You can use the loc gem like this :

require 'loc'

loc1 = Loc::Location[49.1, 2]
loc2 = Loc::Location[50, 3]

loc1.distance_to(loc2)
=> 123364.76538823603 # km

Answer 5

Just a little shorter & separated parameter version of @Lunivore's answer

RAD_PER_DEG = Math::PI / 180
RM = 6371000 # Earth radius in meters

def distance_between(lat1, lon1, lat2, lon2)
  lat1_rad, lat2_rad = lat1 * RAD_PER_DEG, lat2 * RAD_PER_DEG
  lon1_rad, lon2_rad = lon1 * RAD_PER_DEG, lon2 * RAD_PER_DEG

  a = Math.sin((lat2_rad - lat1_rad) / 2) ** 2 + Math.cos(lat1_rad) * Math.cos(lat2_rad) * Math.sin((lon2_rad - lon1_rad) / 2) ** 2
  c = 2 * Math::atan2(Math::sqrt(a), Math::sqrt(1 - a))

  RM * c # Delta in meters
end

Answer 6

You can use the geokit ruby gem. It does these calculations internally, but also supports resolving addresses via google and other services if you need it to.

require 'geokit'

current_location = Geokit::LatLng.new(37.79363,-122.396116)
destination = "37.786217,-122.41619"
current_location.distance_to(destination) 

# Returns distance in miles: 1.211200074136264

You can also find out the bearing_to (direction expressed as a float in degrees between 0-360) and midpoint_to (returns an object you can run .latitude and .longitude methods on).