Haversine Calculator
This is a simple module to help you determine the great-circle distance between two points on a sphere given their longitudes and latitudes o a geojson file.
The formula
This uses the ‘haversine’ formula to calculate the great-circle distance between two points – that is, the shortest distance over the earth’s surface – giving an ‘as-the-crow-flies’ distance between the points (ignoring any hills they fly over, of course!).
Haversine: a = sin²(Δφ/2) + cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2) c
formula: c = 2 ⋅ atan2( √a, √(1−a) ) d = R ⋅ c
where φ is latitude, λ is longitude, R is earth’s radius (mean radius = 6,371km); The angles need to be in radians to pass to trig functions.
Installation
`$ npm install haversine-calculator
Usage of this module
haversine (start, end, options)
const haversineCalculator = require('haversine-calculator')
const start = {
latitude: -23.754842,
longitude: -46.676781
}
const end = {
latitude: -23.549588,
longitude: -46.693210
}
console.log(haversineCalculator(start, end))
console.log(haversineCalculator(start, end, {unit: 'meter'}))
console.log(haversineCalculator(start, end, {unit: 'mile'}))
console.log(haversineCalculator(start, end, {threshold: 1}))
console.log(haversineCalculator(start, end, {threshold: 1, unit: 'meter'}))
console.log(haversineCalculator(start, end, {threshold: 1, unit: 'mile'}))
The api
options.unit
- Unit of measurement applied to result (defaultkm
, availablekm, mile, meter, nmi
)options.threshold
- If passed, will result in library returningboolean
value of whether or not the start and end points are within that supplied threshold. (defaultnull
)options.format
- The format of start and end coordinate arguments. See the table below for available values. (defaultnull
)
Format | Example |
---|---|
undefined (default) |
{ latitude: -23.754842, longitude: -46.676781] } |
[lat,lon] |
[-23.754842, -46.676781] |
[lon,lat] |
[-23.754842, -46.676781] |
{lat,lon} |
{ lat: -23.754842, lon: -46.676781] } |
geojson |
{ type: 'Feature', geometry: { coordinates: [-23.754842, -46.676781] } } |