Question 291860 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – React Calculate Nautical Miles Between Multiple Coordinates

Any ideas on how to calculate the nautical miles using react? Assume that I have an object:

const calculateDistance = [
    {point_id: 1, long: longitude , lat: latitude},
    {point_id: 2, long: longitude , lat: latitude},
    {point_id: 3, long: longitude , lat: latitude},
    {point_id: 4, long: longitude , lat: latitude},
    {point_id: 5, long: longitude , lat: latitude},
]

I would greatly appreciate any suggestions. Thank you!

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2

Answers


  1. 0

    React is a rendering library so you don’t calculate in React. However, you are using javascript or typescript and this you can use. Something like:

    function getDistanceFromLatLonInNauticalMiles(lat1, lon1, lat2, lon2) {
  var R = 6371; // Radius of the earth in km
  var dLat = deg2rad(lat2-lat1);  // deg2rad below
  var dLon = deg2rad(lon2-lon1); 
  var a = 
    Math.sin(dLat/2) * Math.sin(dLat/2) +
    Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * 
    Math.sin(dLon/2) * Math.sin(dLon/2)
    ; 
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
  var d = R * c; // Distance in km
  return d * 0.539957; // convert to nautical miles
}

function deg2rad(deg) {
  return deg * (Math.PI/180)
}

    to calculate between 2 points using the https://en.wikipedia.org/wiki/Haversine_formula then you can add them if you need multiple points.

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  2. 0

    You calculate the distance using the haversine formula in react. Here is how:

    import React, { useState } from "react";
import haversine from "haversine"; //haversine library 

const CalculateDistance = () => {
  const [calculateDistance, setCalculateDistance] = useState([
    { point_id: 1, longitude: -122.4194, latitude: 37.7749 }, //longitude and latitude changed
    { point_id: 2, longitude: -118.2437, latitude: 34.0522 },  //longitude and latitude changed
    { point_id: 3, longitude: -118.2437, latitude: 34.0522 }, //longitude and latitude changed
    { point_id: 4, longitude: -118.2437, latitude: 33.5522 }, //longitude and latitude changed
    { point_id: 5, longitude: -121.4194, latitude: 36.7749 } //changed longitude and latitude
  ]);

  // changed the function to calculateDistance function
  const calculateDistanceValues = () => {
    let totalDistance = 0;
    for (let i = 1; i < calculateDistance.length; i++) {
      const currentPoint = calculateDistance[i - 1];
      const nextPoint = calculateDistance[i];

      const distance = haversine(currentPoint, nextPoint, {
        //longitude and latitude values are used instead of unit 'mi'
        unit: "nmi",
      });
      console.log(distance)
      totalDistance += distance;
    }

    return totalDistance.toFixed(2); // distance need to be fixed to 2 decimal points
  };

  return <div>Total Distance: {calculateDistanceValues()} nm</div>; // distance need to have a  unit of nm
};

    I hope this helps!

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