Turfjs
@turf/helpers
earthRadius
Earth Radius used with the Harvesine formula and approximates using a spherical (non-ellipsoid) Earth.
factors
Unit of measurement factors using a spherical (non-ellipsoid) earth radius.
unitsFactors
Units of measurement factors based on 1 meter.
areaFactors
Area of measurement factors based on 1 square meter.
feature
Wraps a GeoJSON Geometry in a GeoJSON Feature.
Parameters
geometryGeometry input geometrypropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var geometry = {
"type": "Point",
"coordinates": [110, 50]
};
var feature = turf.feature(geometry);
//=featureReturns Feature a GeoJSON Feature
geometry
Creates a GeoJSON Geometry from a Geometry string type & coordinates.
For GeometryCollection type use helpers.geometryCollection
Parameters
typestring Geometry TypecoordinatesArray<number> CoordinatesoptionsObject Optional Parameters (optional, default{})
Examples
var type = 'Point';
var coordinates = [110, 50];
var geometry = turf.geometry(type, coordinates);
//=geometryReturns Geometry a GeoJSON Geometry
point
Creates a Point Feature from a Position.
Parameters
coordinatesArray<number> longitude, latitude position (each in decimal degrees)propertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var point = turf.point([-75.343, 39.984]);
//=pointReturns Feature<Point> a Point feature
points
Creates a Point FeatureCollection from an Array of Point coordinates.
Parameters
coordinatesArray<Array<number>> an array of PointspropertiesObject Translate these properties to each Feature (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var points = turf.points([
[-75, 39],
[-80, 45],
[-78, 50]
]);
//=pointsReturns FeatureCollection<Point> Point Feature
polygon
Creates a Polygon Feature from an Array of LinearRings.
Parameters
coordinatesArray<Array<Array<number>>> an array of LinearRingspropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var polygon = turf.polygon([[[-5, 52], [-4, 56], [-2, 51], [-7, 54], [-5, 52]]], { name: 'poly1' });
//=polygonReturns Feature<Polygon> Polygon Feature
polygons
Creates a Polygon FeatureCollection from an Array of Polygon coordinates.
Parameters
coordinatesArray<Array<Array<Array<number>>>> an array of Polygon coordinatespropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var polygons = turf.polygons([
[[[-5, 52], [-4, 56], [-2, 51], [-7, 54], [-5, 52]]],
[[[-15, 42], [-14, 46], [-12, 41], [-17, 44], [-15, 42]]],
]);
//=polygonsReturns FeatureCollection<Polygon> Polygon FeatureCollection
lineString
Creates a LineString Feature from an Array of Positions.
Parameters
coordinatesArray<Array<number>> an array of PositionspropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var linestring1 = turf.lineString([[-24, 63], [-23, 60], [-25, 65], [-20, 69]], {name: 'line 1'});
var linestring2 = turf.lineString([[-14, 43], [-13, 40], [-15, 45], [-10, 49]], {name: 'line 2'});
//=linestring1
//=linestring2Returns Feature<LineString> LineString Feature
lineStrings
Creates a LineString FeatureCollection from an Array of LineString coordinates.
Parameters
coordinatesArray<Array<number>> an array of LinearRingspropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var linestrings = turf.lineStrings([
[[-24, 63], [-23, 60], [-25, 65], [-20, 69]],
[[-14, 43], [-13, 40], [-15, 45], [-10, 49]]
]);
//=linestringsReturns FeatureCollection<LineString> LineString FeatureCollection
featureCollection
Takes one or more Features and creates a FeatureCollection.
Parameters
Examples
var locationA = turf.point([-75.343, 39.984], {name: 'Location A'});
var locationB = turf.point([-75.833, 39.284], {name: 'Location B'});
var locationC = turf.point([-75.534, 39.123], {name: 'Location C'});
var collection = turf.featureCollection([
locationA,
locationB,
locationC
]);
//=collectionReturns FeatureCollection FeatureCollection of Features
multiLineString
Creates a Feature<MultiLineString> based on a coordinate array. Properties can be added optionally.
Parameters
coordinatesArray<Array<Array<number>>> an array of LineStringspropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var multiLine = turf.multiLineString([[[0,0],[10,10]]]);
//=multiLine- Throws Error if no coordinates are passed
Returns Feature<MultiLineString> a MultiLineString feature
multiPoint
Creates a Feature<MultiPoint> based on a coordinate array. Properties can be added optionally.
Parameters
coordinatesArray<Array<number>> an array of PositionspropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var multiPt = turf.multiPoint([[0,0],[10,10]]);
//=multiPt- Throws Error if no coordinates are passed
Returns Feature<MultiPoint> a MultiPoint feature
multiPolygon
Creates a Feature<MultiPolygon> based on a coordinate array. Properties can be added optionally.
Parameters
coordinatesArray<Array<Array<Array<number>>>> an array of PolygonspropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var multiPoly = turf.multiPolygon([[[[0,0],[0,10],[10,10],[10,0],[0,0]]]]);
//=multiPoly- Throws Error if no coordinates are passed
Returns Feature<MultiPolygon> a multipolygon feature
geometryCollection
Creates a Feature<GeometryCollection> based on a coordinate array. Properties can be added optionally.
Parameters
geometriesArray<Geometry> an array of GeoJSON GeometriespropertiesObject an Object of key-value pairs to add as properties (optional, default{})optionsObject Optional Parameters (optional, default{})
Examples
var pt = {
"type": "Point",
"coordinates": [100, 0]
};
var line = {
"type": "LineString",
"coordinates": [ [101, 0], [102, 1] ]
};
var collection = turf.geometryCollection([pt, line]);
//=collectionReturns Feature<GeometryCollection> a GeoJSON GeometryCollection Feature
round
Round number to precision
Parameters
Examples
turf.round(120.4321)
//=120
turf.round(120.4321, 2)
//=120.43Returns number rounded number
radiansToLength
Convert a distance measurement (assuming a spherical Earth) from radians to a more friendly unit. Valid units: miles, nauticalmiles, inches, yards, meters, metres, kilometers, centimeters, feet
Parameters
radiansnumber in radians across the sphereunitsstring can be degrees, radians, miles, or kilometers inches, yards, metres, meters, kilometres, kilometers. (optional, default'kilometers')
Returns number distance
lengthToRadians
Convert a distance measurement (assuming a spherical Earth) from a real-world unit into radians Valid units: miles, nauticalmiles, inches, yards, meters, metres, kilometers, centimeters, feet
Parameters
distancenumber in real unitsunitsstring can be degrees, radians, miles, or kilometers inches, yards, metres, meters, kilometres, kilometers. (optional, default'kilometers')
Returns number radians
lengthToDegrees
Convert a distance measurement (assuming a spherical Earth) from a real-world unit into degrees Valid units: miles, nauticalmiles, inches, yards, meters, metres, centimeters, kilometres, feet
Parameters
distancenumber in real unitsunitsstring can be degrees, radians, miles, or kilometers inches, yards, metres, meters, kilometres, kilometers. (optional, default'kilometers')
Returns number degrees
bearingToAzimuth
Converts any bearing angle from the north line direction (positive clockwise) and returns an angle between 0-360 degrees (positive clockwise), 0 being the north line
Parameters
bearingnumber angle, between -180 and +180 degrees
Returns number angle between 0 and 360 degrees
radiansToDegrees
Converts an angle in radians to degrees
Parameters
radiansnumber angle in radians
Returns number degrees between 0 and 360 degrees
degreesToRadians
Converts an angle in degrees to radians
Parameters
degreesnumber angle between 0 and 360 degrees
Returns number angle in radians
convertLength
Converts a length to the requested unit. Valid units: miles, nauticalmiles, inches, yards, meters, metres, kilometers, centimeters, feet
Parameters
lengthnumber to be convertedoriginalUnitstring of the lengthfinalUnitstring returned unit (optional, default'kilometers')
Returns number the converted length
convertArea
Converts a area to the requested unit. Valid units: kilometers, kilometres, meters, metres, centimetres, millimeters, acres, miles, yards, feet, inches
Parameters
areanumber to be convertedoriginalUnitstring of the distance (optional, default'meters')finalUnitstring returned unit (optional, default'kilometers')
Returns number the converted distance
isNumber
isNumber
Parameters
numany Number to validate
Examples
turf.isNumber(123)
//=true
turf.isNumber('foo')
//=falseReturns boolean true/false
isObject
isObject
Parameters
inputany variable to validate
Examples
turf.isObject({elevation: 10})
//=true
turf.isObject('foo')
//=falseReturns boolean true/false
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 module individually:
$ npm install @turf/helpersOr install the Turf module that includes it as a function:
$ npm install @turf/turf