Turfjs
@turf/meta
coordEachCallback
Callback for coordEach
Type: Function
Parameters
currentCoordArray<number> The current coordinate being processed.coordIndexnumber The current index of the coordinate being processed.featureIndexnumber The current index of the Feature being processed.multiFeatureIndexnumber The current index of the Multi-Feature being processed.geometryIndexnumber The current index of the Geometry being processed.
Returns void
coordEach
Iterate over coordinates in any GeoJSON object, similar to Array.forEach()
Parameters
geojsonAllGeoJSON any GeoJSON objectcallbackcoordEachCallback a method that takes (currentCoord, coordIndex, featureIndex, multiFeatureIndex)excludeWrapCoordboolean whether or not to include the final coordinate of LinearRings that wraps the ring in its iteration. (optional, defaultfalse)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {"foo": "bar"}),
turf.point([36, 53], {"hello": "world"})
]);
turf.coordEach(features, function (currentCoord, coordIndex, featureIndex, multiFeatureIndex, geometryIndex) {
//=currentCoord
//=coordIndex
//=featureIndex
//=multiFeatureIndex
//=geometryIndex
});Returns void
coordReduceCallback
Callback for coordReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentCoordArray<number> The current coordinate being processed.coordIndexnumber The current index of the coordinate being processed. Starts at index 0, if an initialValue is provided, and at index 1 otherwise.featureIndexnumber The current index of the Feature being processed.multiFeatureIndexnumber The current index of the Multi-Feature being processed.geometryIndexnumber The current index of the Geometry being processed.
Returns Reducer
coordReduce
Reduce coordinates in any GeoJSON object, similar to Array.reduce()
Parameters
geojsonAllGeoJSON any GeoJSON objectcallbackcoordReduceCallback a method that takes (previousValue, currentCoord, coordIndex)initialValueReducer? Value to use as the first argument to the first call of the callback.excludeWrapCoordboolean whether or not to include the final coordinate of LinearRings that wraps the ring in its iteration. (optional, defaultfalse)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {"foo": "bar"}),
turf.point([36, 53], {"hello": "world"})
]);
turf.coordReduce(features, function (previousValue, currentCoord, coordIndex, featureIndex, multiFeatureIndex, geometryIndex) {
//=previousValue
//=currentCoord
//=coordIndex
//=featureIndex
//=multiFeatureIndex
//=geometryIndex
return currentCoord;
});Returns Reducer The value that results from the reduction.
propEachCallback
Callback for propEach
Type: Function
Parameters
currentPropertiesGeoJsonProperties The current Properties being processed.featureIndexnumber The current index of the Feature being processed.
Returns void
propEach
Iterate over properties in any GeoJSON object, similar to Array.forEach()
Parameters
geojson(FeatureCollection | Feature) any GeoJSON objectcallbackpropEachCallback a method that takes (currentProperties, featureIndex)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.propEach(features, function (currentProperties, featureIndex) {
//=currentProperties
//=featureIndex
});Returns void
propReduceCallback
Callback for propReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentPropertiesGeoJsonProperties The current Properties being processed.featureIndexnumber The current index of the Feature being processed.
Returns Reducer
propReduce
Reduce properties in any GeoJSON object into a single value, similar to how Array.reduce works. However, in this case we lazily run the reduction, so an array of all properties is unnecessary.
Parameters
geojson(FeatureCollection | Feature | Geometry) any GeoJSON objectcallbackpropReduceCallback a method that takes (previousValue, currentProperties, featureIndex)initialValueReducer? Value to use as the first argument to the first call of the callback.
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.propReduce(features, function (previousValue, currentProperties, featureIndex) {
//=previousValue
//=currentProperties
//=featureIndex
return currentProperties
});Returns Reducer The value that results from the reduction.
featureEachCallback
Callback for featureEach
Type: Function
Parameters
currentFeatureFeature<any> The current Feature being processed.featureIndexnumber The current index of the Feature being processed.
Returns void
featureEach
Iterate over features in any GeoJSON object, similar to Array.forEach.
Parameters
geojson(FeatureCollection | Feature | Feature<GeometryCollection>) any GeoJSON objectcallbackfeatureEachCallback a method that takes (currentFeature, featureIndex)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.featureEach(features, function (currentFeature, featureIndex) {
//=currentFeature
//=featureIndex
});Returns void
featureReduceCallback
Callback for featureReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentFeatureFeature The current Feature being processed.featureIndexnumber The current index of the Feature being processed.
Returns Reducer
featureReduce
Reduce features in any GeoJSON object, similar to Array.reduce().
Parameters
geojson(FeatureCollection | Feature | Feature<GeometryCollection>) any GeoJSON objectcallbackfeatureReduceCallback a method that takes (previousValue, currentFeature, featureIndex)initialValueReducer? Value to use as the first argument to the first call of the callback.
Examples
var features = turf.featureCollection([
turf.point([26, 37], {"foo": "bar"}),
turf.point([36, 53], {"hello": "world"})
]);
turf.featureReduce(features, function (previousValue, currentFeature, featureIndex) {
//=previousValue
//=currentFeature
//=featureIndex
return currentFeature
});Returns Reducer The value that results from the reduction.
coordAll
Get all coordinates from any GeoJSON object.
Parameters
geojsonAllGeoJSON any GeoJSON object
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
var coords = turf.coordAll(features);
//= [[26, 37], [36, 53]]Returns Array<Array<number>> coordinate position array
geomEachCallback
Callback for geomEach
Type: Function
Parameters
currentGeometryGeometryObject The current Geometry being processed.featureIndexnumber The current index of the Feature being processed.featurePropertiesGeoJsonProperties The current Feature Properties being processed.featureBBoxBBox The current Feature BBox being processed.featureIdId The current Feature Id being processed.
Returns void
geomEach
Iterate over each geometry in any GeoJSON object, similar to Array.forEach()
Parameters
geojson(FeatureCollection | Feature | Geometry | GeometryObject | Feature<GeometryCollection>) any GeoJSON objectcallbackgeomEachCallback a method that takes (currentGeometry, featureIndex, featureProperties, featureBBox, featureId)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.geomEach(features, function (currentGeometry, featureIndex, featureProperties, featureBBox, featureId) {
//=currentGeometry
//=featureIndex
//=featureProperties
//=featureBBox
//=featureId
});Returns void
geomReduceCallback
Callback for geomReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentGeometryGeometryObject The current Geometry being processed.featureIndexnumber The current index of the Feature being processed.featurePropertiesGeoJsonProperties The current Feature Properties being processed.featureBBoxBBox The current Feature BBox being processed.featureIdId The current Feature Id being processed.
Returns Reducer
geomReduce
Reduce geometry in any GeoJSON object, similar to Array.reduce().
Parameters
geojson(FeatureCollection | Feature | GeometryObject | GeometryCollection | Feature<GeometryCollection>) any GeoJSON objectcallbackgeomReduceCallback a method that takes (previousValue, currentGeometry, featureIndex, featureProperties, featureBBox, featureId)initialValueReducer? Value to use as the first argument to the first call of the callback.
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.geomReduce(features, function (previousValue, currentGeometry, featureIndex, featureProperties, featureBBox, featureId) {
//=previousValue
//=currentGeometry
//=featureIndex
//=featureProperties
//=featureBBox
//=featureId
return currentGeometry
});Returns Reducer The value that results from the reduction.
flattenEachCallback
Callback for flattenEach
Type: Function
Parameters
currentFeatureFeature The current flattened feature being processed.featureIndexnumber The current index of the Feature being processed.multiFeatureIndexnumber The current index of the Multi-Feature being processed.
Returns void
flattenEach
Iterate over flattened features in any GeoJSON object, similar to Array.forEach.
Parameters
geojson(FeatureCollection | Feature | GeometryObject | GeometryCollection | Feature<GeometryCollection>) any GeoJSON objectcallbackflattenEachCallback a method that takes (currentFeature, featureIndex, multiFeatureIndex)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.multiPoint([[40, 30], [36, 53]], {hello: 'world'})
]);
turf.flattenEach(features, function (currentFeature, featureIndex, multiFeatureIndex) {
//=currentFeature
//=featureIndex
//=multiFeatureIndex
});Returns void
flattenReduceCallback
Callback for flattenReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentFeatureFeature The current Feature being processed.featureIndexnumber The current index of the Feature being processed.multiFeatureIndexnumber The current index of the Multi-Feature being processed.
Returns Reducer
flattenReduce
Reduce flattened features in any GeoJSON object, similar to Array.reduce().
Parameters
geojson(FeatureCollection | Feature | GeometryObject | GeometryCollection | Feature<GeometryCollection>) any GeoJSON objectcallbackflattenReduceCallback a method that takes (previousValue, currentFeature, featureIndex, multiFeatureIndex)initialValueReducer? Value to use as the first argument to the first call of the callback.
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.multiPoint([[40, 30], [36, 53]], {hello: 'world'})
]);
turf.flattenReduce(features, function (previousValue, currentFeature, featureIndex, multiFeatureIndex) {
//=previousValue
//=currentFeature
//=featureIndex
//=multiFeatureIndex
return currentFeature
});Returns Reducer The value that results from the reduction.
segmentEachCallback
Callback for segmentEach
Type: Function
Parameters
currentSegmentFeature<LineString> The current Segment being processed.featureIndexnumber The current index of the Feature being processed.multiFeatureIndexnumber The current index of the Multi-Feature being processed.geometryIndexnumber The current index of the Geometry being processed.segmentIndexnumber The current index of the Segment being processed.
Returns void
segmentEach
Iterate over 2-vertex line segment in any GeoJSON object, similar to Array.forEach() (Multi)Point geometries do not contain segments therefore they are ignored during this operation.
Parameters
geojsonAllGeoJSON any GeoJSONcallbacksegmentEachCallback a method that takes (currentSegment, featureIndex, multiFeatureIndex, geometryIndex, segmentIndex)
Examples
var polygon = turf.polygon([[[-50, 5], [-40, -10], [-50, -10], [-40, 5], [-50, 5]]]);
// Iterate over GeoJSON by 2-vertex segments
turf.segmentEach(polygon, function (currentSegment, featureIndex, multiFeatureIndex, geometryIndex, segmentIndex) {
//=currentSegment
//=featureIndex
//=multiFeatureIndex
//=geometryIndex
//=segmentIndex
});
// Calculate the total number of segments
var total = 0;
turf.segmentEach(polygon, function () {
total++;
});Returns void
segmentReduceCallback
Callback for segmentReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentSegmentFeature<LineString> The current Segment being processed.featureIndexnumber The current index of the Feature being processed.multiFeatureIndexnumber The current index of the Multi-Feature being processed.geometryIndexnumber The current index of the Geometry being processed.segmentIndexnumber The current index of the Segment being processed.
Returns Reducer
segmentReduce
Reduce 2-vertex line segment in any GeoJSON object, similar to Array.reduce() (Multi)Point geometries do not contain segments therefore they are ignored during this operation.
Parameters
geojson(FeatureCollection | Feature | Geometry) any GeoJSONcallbacksegmentReduceCallback a method that takes (previousValue, currentSegment, currentIndex)initialValueReducer? Value to use as the first argument to the first call of the callback.
Examples
var polygon = turf.polygon([[[-50, 5], [-40, -10], [-50, -10], [-40, 5], [-50, 5]]]);
// Iterate over GeoJSON by 2-vertex segments
turf.segmentReduce(polygon, function (previousSegment, currentSegment, featureIndex, multiFeatureIndex, geometryIndex, segmentIndex) {
//= previousSegment
//= currentSegment
//= featureIndex
//= multiFeatureIndex
//= geometryIndex
//= segmentIndex
return currentSegment
});
// Calculate the total number of segments
var initialValue = 0
var total = turf.segmentReduce(polygon, function (previousValue) {
previousValue++;
return previousValue;
}, initialValue);Returns Reducer
lineEachCallback
Callback for lineEach
Type: Function
Parameters
currentLineFeature<LineString> The current LineString|LinearRing being processedfeatureIndexnumber The current index of the Feature being processedmultiFeatureIndexnumber The current index of the Multi-Feature being processedgeometryIndexnumber The current index of the Geometry being processed
Returns void
lineEach
Iterate over line or ring coordinates in LineString, Polygon, MultiLineString, MultiPolygon Features or Geometries, similar to Array.forEach.
Parameters
geojson(FeatureCollection<Lines> | Feature<Lines> | Lines | Feature<GeometryCollection> | GeometryCollection) objectcallbacklineEachCallback a method that takes (currentLine, featureIndex, multiFeatureIndex, geometryIndex)
Examples
var multiLine = turf.multiLineString([
[[26, 37], [35, 45]],
[[36, 53], [38, 50], [41, 55]]
]);
turf.lineEach(multiLine, function (currentLine, featureIndex, multiFeatureIndex, geometryIndex) {
//=currentLine
//=featureIndex
//=multiFeatureIndex
//=geometryIndex
});Returns void
lineReduceCallback
Callback for lineReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
- The previousValue argument is initialValue.
- The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
- The previousValue argument is the value of the first element present in the array.
- The currentValue argument is the value of the second element present in the array.
Type: Function
Parameters
previousValueReducer The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied.currentLineFeature<LineString> The current LineString|LinearRing being processed.featureIndexnumber The current index of the Feature being processedmultiFeatureIndexnumber The current index of the Multi-Feature being processedgeometryIndexnumber The current index of the Geometry being processed
Returns Reducer
lineReduce
Reduce features in any GeoJSON object, similar to Array.reduce().
Parameters
geojson(FeatureCollection<Lines> | Feature<Lines> | Lines | Feature<GeometryCollection> | GeometryCollection) objectcallbackFunction a method that takes (previousValue, currentLine, featureIndex, multiFeatureIndex, geometryIndex)initialValueReducer? Value to use as the first argument to the first call of the callback.
Examples
var multiPoly = turf.multiPolygon([
turf.polygon([[[12,48],[2,41],[24,38],[12,48]], [[9,44],[13,41],[13,45],[9,44]]]),
turf.polygon([[[5, 5], [0, 0], [2, 2], [4, 4], [5, 5]]])
]);
turf.lineReduce(multiPoly, function (previousValue, currentLine, featureIndex, multiFeatureIndex, geometryIndex) {
//=previousValue
//=currentLine
//=featureIndex
//=multiFeatureIndex
//=geometryIndex
return currentLine
});Returns Reducer The value that results from the reduction.
findSegment
Finds a particular 2-vertex LineString Segment from a GeoJSON using @turf/meta indexes.
Negative indexes are permitted. Point & MultiPoint will always return null.
Parameters
geojson(FeatureCollection | Feature | Geometry) Any GeoJSON Feature or GeometryoptionsObject Optional parameters (optional, default{})options.featureIndexnumber Feature Index (optional, default0)options.multiFeatureIndexnumber Multi-Feature Index (optional, default0)options.geometryIndexnumber Geometry Index (optional, default0)options.segmentIndexnumber Segment Index (optional, default0)options.propertiesObject Translate Properties to output LineString (optional, default{})options.bboxBBox Translate BBox to output LineString (optional, default{})options.id(number | string) Translate Id to output LineString (optional, default{})
Examples
var multiLine = turf.multiLineString([
[[10, 10], [50, 30], [30, 40]],
[[-10, -10], [-50, -30], [-30, -40]]
]);
// First Segment (defaults are 0)
turf.findSegment(multiLine);
// => Feature<LineString<[[10, 10], [50, 30]]>>
// First Segment of 2nd Multi Feature
turf.findSegment(multiLine, {multiFeatureIndex: 1});
// => Feature<LineString<[[-10, -10], [-50, -30]]>>
// Last Segment of Last Multi Feature
turf.findSegment(multiLine, {multiFeatureIndex: -1, segmentIndex: -1});
// => Feature<LineString<[[-50, -30], [-30, -40]]>>Returns Feature<LineString> 2-vertex GeoJSON Feature LineString
findPoint
Finds a particular Point from a GeoJSON using @turf/meta indexes.
Negative indexes are permitted.
Parameters
geojson(FeatureCollection | Feature | Geometry) Any GeoJSON Feature or GeometryoptionsObject Optional parameters (optional, default{})options.featureIndexnumber Feature Index (optional, default0)options.multiFeatureIndexnumber Multi-Feature Index (optional, default0)options.geometryIndexnumber Geometry Index (optional, default0)options.coordIndexnumber Coord Index (optional, default0)options.propertiesObject Translate Properties to output Point (optional, default{})options.bboxBBox Translate BBox to output Point (optional, default{})options.id(number | string) Translate Id to output Point (optional, default{})
Examples
var multiLine = turf.multiLineString([
[[10, 10], [50, 30], [30, 40]],
[[-10, -10], [-50, -30], [-30, -40]]
]);
// First Segment (defaults are 0)
turf.findPoint(multiLine);
// => Feature<Point<[10, 10]>>
// First Segment of the 2nd Multi-Feature
turf.findPoint(multiLine, {multiFeatureIndex: 1});
// => Feature<Point<[-10, -10]>>
// Last Segment of last Multi-Feature
turf.findPoint(multiLine, {multiFeatureIndex: -1, coordIndex: -1});
// => Feature<Point<[-30, -40]>>Returns Feature<Point> 2-vertex GeoJSON Feature Point
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/metaOr install the all-encompassing @turf/turf module that includes all modules as functions:
$ npm install @turf/turf