| 1 | 1 | 'use strict'; |
| 2 | | |
| 3 | 1 | var haversine = module.exports = {}; |
| 4 | | |
| 5 | | |
| 6 | | // ----- configurable earthRadius |
| 7 | | // --------------------------------------- |
| 8 | 1 | haversine.earthRadius = 6371000; |
| 9 | | |
| 10 | | |
| 11 | | // ----- convert degrees to radians |
| 12 | | // --------------------------------------- |
| 13 | 1 | haversine.degreesToRadians = function(deg) { |
| 14 | 16 | return deg * (Math.PI / 180); |
| 15 | | }; |
| 16 | | |
| 17 | | |
| 18 | | // ----- distance between two points |
| 19 | | // --------------------------------------- |
| 20 | 1 | haversine.distance = function(lat1, lon1, lat2, lon2) { |
| 21 | | |
| 22 | 3 | var latitudeDifference = this.degreesToRadians(lat2 - lat1); |
| 23 | 3 | var logitudeDifference = this.degreesToRadians(lon2 - lon1); |
| 24 | | |
| 25 | 3 | var haversine = |
| 26 | | Math.sin(latitudeDifference/2) * Math.sin(latitudeDifference/2) + |
| 27 | | Math.cos(this.degreesToRadians(lat1)) * Math.cos(this.degreesToRadians(lat2)) * |
| 28 | | Math.sin(logitudeDifference/2) * Math.sin(logitudeDifference/2); |
| 29 | | |
| 30 | 3 | var distance = 2 * Math.atan2(Math.sqrt(haversine), Math.sqrt(1 - haversine)); |
| 31 | | |
| 32 | 3 | return this.earthRadius * distance; |
| 33 | | |
| 34 | | }; |
| 35 | | |
| 36 | | |
| 37 | | // ----- convert degrees/minutes/seconds to decimal degrees |
| 38 | | // --------------------------------------- |
| 39 | 1 | haversine.toDecimal = function(str) { |
| 40 | | |
| 41 | 8 | str = str.toLowerCase(); // throws if input is not a string |
| 42 | 8 | var lastChar = str.slice(-1); |
| 43 | 8 | var negative = false; |
| 44 | | |
| 45 | 8 | if (lastChar === 'w' || lastChar === 's') { |
| 46 | 2 | negative = true; // south and west => negative |
| 47 | | } |
| 48 | | |
| 49 | 8 | var values = str.split(/[^0-9.]/); |
| 50 | 8 | var i; |
| 51 | | // convert strings to numbers |
| 52 | 8 | for (i = 0; i < values.length; i++) { |
| 53 | | |
| 54 | | // remove empty values |
| 55 | 27 | if (!values[i]) { |
| 56 | 8 | values.splice(i, 1); |
| 57 | 8 | continue; |
| 58 | | } |
| 59 | | |
| 60 | 19 | values[i] = parseFloat(values[i]); |
| 61 | | |
| 62 | | } |
| 63 | | |
| 64 | | // make sure array has length 3 |
| 65 | 8 | for (i = 0; i < 3; i++) { |
| 66 | 24 | values[i] = values[i] || 0; |
| 67 | | } |
| 68 | | |
| 69 | 8 | var result = values[0] + (values[1] / 60) + (values[2] / 3600); |
| 70 | | |
| 71 | 8 | if (negative) { |
| 72 | 2 | return result * -1; |
| 73 | | } |
| 74 | | |
| 75 | 6 | return result; |
| 76 | | |
| 77 | | }; |