turf/packages/turf-isolines

@turf/isolines

isolines

Takes a grid FeatureCollection of Point features with z-values and an array of value breaks and generates isolines.

Parameters

• pointGrid FeatureCollection<Point> input points - must be square or rectangular and already gridded. That is, to have consistent x and y dimensions and be at least 2x2 in size.

• breaks Array<number> values of zProperty where to draw isolines

• options Object Optional parameters (optional, default {})

  • options.zProperty string the property name in points from which z-values will be pulled (optional, default 'elevation')
  • options.commonProperties Object GeoJSON properties passed to ALL isolines (optional, default {})
  • options.breaksProperties Array<Object> GeoJSON properties passed, in order, to the correspondent isoline; the breaks array will define the order in which the isolines are created (optional, default [])

Examples

// create a grid of points with random z-values in their properties
var extent = [0, 30, 20, 50];
var cellWidth = 100;
var pointGrid = turf.pointGrid(extent, cellWidth, {units: 'miles'});

for (var i = 0; i < pointGrid.features.length; i++) {
    pointGrid.features[i].properties.temperature = Math.random() * 10;
}
var breaks = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

var lines = turf.isolines(pointGrid, breaks, {zProperty: 'temperature'});

//addToMap
var addToMap = [lines];

Returns FeatureCollection<MultiLineString> a FeatureCollection of MultiLineString features representing isolines

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This module is part of the Turfjs project, an open source module collection dedicated to geographic algorithms. It is maintained in the Turfjs/turf repository, where you can create PRs and issues.

Installation

Install this single module individually:

$ npm install @turf/isolines

Or install the all-encompassing @turf/turf module that includes all modules as functions:

$ npm install @turf/turf