geo-points-and-paths/examples/path.js

Simple classes to handle and calculate derived properties of geographic points and paths, such as distance etc. Also allows simplification of paths and storage of multiple parameters on the points.

const Path = require('../index').Path;
const Point = require('../index').Point;
const data = require('./data');
const coords = data.coords;
const points = coords.map( c => new Point(c));
const elevs = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 ];
const HR = [ 11, 22, 33, 44, 55, 66, 77, 88, 99, 109, 119, 129, 139, 149, 159, 196, 179, 189, 199, 209 ];
const powerWrongLength = [ 20, 30, 40, 50, 60, 70, 80];

// Instantiate a Path - must be an array of points- point-like objects are not accepted because the Path
// class needs access to the methods on the Point class to fulfil its functions
let path = new Path(points);

// Add a parameter to the path
path.addParamToPoints('elev', elevs);   // adds each elevation onto the point instances
path.addParamToPoints('HR', HR);        // adds each HR onto the point instances
path.addParamToPoints('HR', elevs);     // does nothing because HR is already set and not overwritten
try {
  path.addParamToPoints('power', powerWrongLength);     // returns error as incorrect param array length
} catch(err) {
  console.log(err.message)
}
console.log(path);

// Delete a parameter from the path
path.deleteParamFromPoints('HR');   // adds each elevation onto the point instances
path.deleteParamFromPoints('lat');   // ignored without error - cannot delete lat or lng
console.log(path);

// Get an array of values for a provided parameter
console.log(path.getParamFromPoints('elev'));
console.log(path.getParamFromPoints('HR'));    // returns undefined if the param does not exist

// Get a point at a given index
console.log(path.getPoint(3));
try {
  path.getPoint(30);                            // returns error because index is out of range
} catch(err) {  
  console.log(err.message)
}

// Other getters
console.log(path.lngLats);              // simple array of [lng,lat] coordinates
console.log(path.length);               // number of points in the path
console.log(path.boundingBox);          // bounding box as {minLat, minLng, maxLat, maxLng}
console.log(path.deltaDistance);        // array with distance between each succcessive point
console.log(path.cumulativeDistance);   // array with cumulative distance between each point
console.log(path.distance);             // total distance of the path
console.log(path.simplificationRatio);  // simplification ratio (simplified length / original length)

// Simplify path
path.simplify(3);
console.log(path.lngLats);              // simple array of [lng,lat] coordinates
console.log(path.length);               // number of points in the path
console.log(path.boundingBox);          // bounding box as {minLat, minLng, maxLat, maxLng}
console.log(path.deltaDistance);        // array with distance between each succcessive point
console.log(path.cumulativeDistance);   // array with cumulative distance between each point
console.log(path.distance);             // total distance of the path
console.log(path.simplificationRatio);  // simplification ratio (simplified length / original length)