Provides tools for iterating over and manipulating GeoJSON objects.
npm install @turf/metaCallback for coordEach
Type: [Function][1]
* currentCoord [Array][2]<[number][3]> The current coordinate being processed.
* coordIndex [number][3] The current index of the coordinate being processed.
* featureIndex [number][3] The current index of the Feature being processed.
* multiFeatureIndex [number][3] The current index of the Multi-Feature being processed.
* geometryIndex [number][3] The current index of the Geometry being processed.
Returns void
Iterate over coordinates in any GeoJSON object, similar to Array.forEach()
* geojson AllGeoJSON any GeoJSON object
* callback [coordEachCallback][4] a method that takes (currentCoord, coordIndex, featureIndex, multiFeatureIndex)
* excludeWrapCoord [boolean][5] whether or not to include the final coordinate of LinearRings that wraps the ring in its iteration. (optional, default false)
``javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentCoord
of the callback, or initialValue, if supplied.
* [Array][2]<[number][3]> The current coordinate being processed.coordIndex
* [number][3] The current index of the coordinate being processed.featureIndex
Starts at index 0, if an initialValue is provided, and at index 1 otherwise.
* [number][3] The current index of the Feature being processed.multiFeatureIndex
* [number][3] The current index of the Multi-Feature being processed.geometryIndex
* [number][3] The current index of the Geometry being processed.
Returns Reducer
Reduce coordinates in any GeoJSON object, similar to Array.reduce()
* geojson AllGeoJSON any GeoJSON objectcallback
* [coordReduceCallback][6] a method that takes (previousValue, currentCoord, coordIndex)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.excludeWrapCoord
* [boolean][5] whether or not to include the final coordinate of LinearRings that wraps the ring in its iteration. (optional, default false)
`javascript
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.
Callback for propEach
Type: [Function][1]
* currentProperties [GeoJsonProperties][7] The current Properties being processed.featureIndex
* [number][3] The current index of the Feature being processed.
Returns void
Iterate over properties in any GeoJSON object, similar to Array.forEach()
* geojson ([FeatureCollection][8] | [Feature][7]) any GeoJSON objectcallback
* [propEachCallback][9] a method that takes (currentProperties, featureIndex)
`javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentProperties
of the callback, or initialValue, if supplied.
* [GeoJsonProperties][7] The current Properties being processed.featureIndex
* [number][3] The current index of the Feature being processed.
Returns Reducer
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.
* geojson ([FeatureCollection][8] | [Feature][7] | [Geometry][10]) any GeoJSON objectcallback
* [propReduceCallback][11] a method that takes (previousValue, currentProperties, featureIndex)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.
`javascript
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.
Callback for featureEach
Type: [Function][1]
* currentFeature [Feature][7]\featureIndex
* [number][3] The current index of the Feature being processed.
Returns void
Iterate over features in any GeoJSON object, similar to
Array.forEach.
* geojson ([FeatureCollection][8] | [Feature][7] | [Feature][7]<[GeometryCollection][12]>) any GeoJSON objectcallback
* [featureEachCallback][13] a method that takes (currentFeature, featureIndex)
`javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentFeature
of the callback, or initialValue, if supplied.
* [Feature][7] The current Feature being processed.featureIndex
* [number][3] The current index of the Feature being processed.
Returns Reducer
Reduce features in any GeoJSON object, similar to Array.reduce().
* geojson ([FeatureCollection][8] | [Feature][7] | [Feature][7]<[GeometryCollection][12]>) any GeoJSON objectcallback
* [featureReduceCallback][14] a method that takes (previousValue, currentFeature, featureIndex)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.
`javascript
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.
Get all coordinates from any GeoJSON object.
* geojson AllGeoJSON any GeoJSON object
`javascript
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][2]<[Array][2]<[number][3]>> coordinate position array
Callback for geomEach
Type: [Function][1]
* currentGeometry [GeometryObject][10] The current Geometry being processed.featureIndex
* [number][3] The current index of the Feature being processed.featureProperties
* [GeoJsonProperties][7] The current Feature Properties being processed.featureBBox
* [BBox][15] The current Feature BBox being processed.featureId
* Id The current Feature Id being processed.
Returns void
Iterate over each geometry in any GeoJSON object, similar to Array.forEach()
* geojson ([FeatureCollection][8] | [Feature][7] | [Geometry][10] | [GeometryObject][10] | [Feature][7]<[GeometryCollection][12]>) any GeoJSON objectcallback
* [geomEachCallback][16] a method that takes (currentGeometry, featureIndex, featureProperties, featureBBox, featureId)
`javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentGeometry
of the callback, or initialValue, if supplied.
* [GeometryObject][10] The current Geometry being processed.featureIndex
* [number][3] The current index of the Feature being processed.featureProperties
* [GeoJsonProperties][7] The current Feature Properties being processed.featureBBox
* [BBox][15] The current Feature BBox being processed.featureId
* Id The current Feature Id being processed.
Returns Reducer
Reduce geometry in any GeoJSON object, similar to Array.reduce().
* geojson ([FeatureCollection][8] | [Feature][7] | [GeometryObject][10] | [GeometryCollection][12] | [Feature][7]<[GeometryCollection][12]>) any GeoJSON objectcallback
* [geomReduceCallback][17] a method that takes (previousValue, currentGeometry, featureIndex, featureProperties, featureBBox, featureId)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.
`javascript
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.
Callback for flattenEach
Type: [Function][1]
* currentFeature [Feature][7] The current flattened feature being processed.featureIndex
* [number][3] The current index of the Feature being processed.multiFeatureIndex
* [number][3] The current index of the Multi-Feature being processed.
Returns void
Iterate over flattened features in any GeoJSON object, similar to
Array.forEach.
* geojson ([FeatureCollection][8] | [Feature][7] | [GeometryObject][10] | [GeometryCollection][12] | [Feature][7]<[GeometryCollection][12]>) any GeoJSON objectcallback
* [flattenEachCallback][18] a method that takes (currentFeature, featureIndex, multiFeatureIndex)
`javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentFeature
of the callback, or initialValue, if supplied.
* [Feature][7] The current Feature being processed.featureIndex
* [number][3] The current index of the Feature being processed.multiFeatureIndex
* [number][3] The current index of the Multi-Feature being processed.
Returns Reducer
Reduce flattened features in any GeoJSON object, similar to Array.reduce().
* geojson ([FeatureCollection][8] | [Feature][7] | [GeometryObject][10] | [GeometryCollection][12] | [Feature][7]<[GeometryCollection][12]>) any GeoJSON objectcallback
* [flattenReduceCallback][19] a method that takes (previousValue, currentFeature, featureIndex, multiFeatureIndex)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.
`javascript
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.
Callback for segmentEach
Type: [Function][1]
* currentSegment [Feature][7]<[LineString][20]> The current Segment being processed.featureIndex
* [number][3] The current index of the Feature being processed.multiFeatureIndex
* [number][3] The current index of the Multi-Feature being processed.geometryIndex
* [number][3] The current index of the Geometry being processed.segmentIndex
* [number][3] The current index of the Segment being processed.
Returns void
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.
* geojson AllGeoJSON any GeoJSONcallback
* [segmentEachCallback][21] a method that takes (currentSegment, featureIndex, multiFeatureIndex, geometryIndex, segmentIndex)
`javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentSegment
of the callback, or initialValue, if supplied.
* [Feature][7]<[LineString][20]> The current Segment being processed.featureIndex
* [number][3] The current index of the Feature being processed.multiFeatureIndex
* [number][3] The current index of the Multi-Feature being processed.geometryIndex
* [number][3] The current index of the Geometry being processed.segmentIndex
* [number][3] The current index of the Segment being processed.
Returns Reducer
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.
* geojson ([FeatureCollection][8] | [Feature][7] | [Geometry][10]) any GeoJSONcallback
* [segmentReduceCallback][22] a method that takes (previousValue, currentSegment, currentIndex)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.
`javascript
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
Callback for lineEach
Type: [Function][1]
* currentLine [Feature][7]<[LineString][20]> The current LineString|LinearRing being processedfeatureIndex
* [number][3] The current index of the Feature being processedmultiFeatureIndex
* [number][3] The current index of the Multi-Feature being processedgeometryIndex
* [number][3] The current index of the Geometry being processed
Returns void
Iterate over line or ring coordinates in LineString, Polygon, MultiLineString, MultiPolygon Features or Geometries,
similar to Array.forEach.
* geojson ([FeatureCollection][8]\callback
* [lineEachCallback][23] a method that takes (currentLine, featureIndex, multiFeatureIndex, geometryIndex)
`javascript
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
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][1]
* previousValue Reducer The accumulated value previously returned in the last invocationcurrentLine
of the callback, or initialValue, if supplied.
* [Feature][7]<[LineString][20]> The current LineString|LinearRing being processed.featureIndex
* [number][3] The current index of the Feature being processedmultiFeatureIndex
* [number][3] The current index of the Multi-Feature being processedgeometryIndex
* [number][3] The current index of the Geometry being processed
Returns Reducer
Reduce features in any GeoJSON object, similar to Array.reduce().
* geojson ([FeatureCollection][8]\callback
* [Function][1] a method that takes (previousValue, currentLine, featureIndex, multiFeatureIndex, geometryIndex)initialValue
* Reducer? Value to use as the first argument to the first call of the callback.
`javascript
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.
Finds a particular 2-vertex LineString Segment from a GeoJSON using @turf/meta indexes.
Negative indexes are permitted.
Point & MultiPoint will always return null.
* geojson ([FeatureCollection][8] | [Feature][7] | [Geometry][10]) Any GeoJSON Feature or Geometryoptions
* [Object][24] Optional parameters (optional, default {})
* options.featureIndex [number][3] Feature Index (optional, default 0)options.multiFeatureIndex
* [number][3] Multi-Feature Index (optional, default 0)options.geometryIndex
* [number][3] Geometry Index (optional, default 0)options.segmentIndex
* [number][3] Segment Index (optional, default 0)options.properties
* [Object][24] Translate Properties to output LineString (optional, default {})options.bbox
* [BBox][15] Translate BBox to output LineString (optional, default {})options.id
* ([number][3] | [string][25]) Translate Id to output LineString (optional, default {})
`javascript
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
// First Segment of 2nd Multi Feature
turf.findSegment(multiLine, {multiFeatureIndex: 1});
// => Feature
// Last Segment of Last Multi Feature
turf.findSegment(multiLine, {multiFeatureIndex: -1, segmentIndex: -1});
// => Feature
`
Returns [Feature][7]<[LineString][20]> 2-vertex GeoJSON Feature LineString
Finds a particular Point from a GeoJSON using @turf/meta indexes.
Negative indexes are permitted.
* geojson ([FeatureCollection][8] | [Feature][7] | [Geometry][10]) Any GeoJSON Feature or Geometryoptions
* [Object][24] Optional parameters (optional, default {})
* options.featureIndex [number][3] Feature Index (optional, default 0)options.multiFeatureIndex
* [number][3] Multi-Feature Index (optional, default 0)options.geometryIndex
* [number][3] Geometry Index (optional, default 0)options.coordIndex
* [number][3] Coord Index (optional, default 0)options.properties
* [Object][24] Translate Properties to output Point (optional, default {})options.bbox
* [BBox][15] Translate BBox to output Point (optional, default {})options.id
* ([number][3] | [string][25]) Translate Id to output Point (optional, default {})
`javascript
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
// First Segment of the 2nd Multi-Feature
turf.findPoint(multiLine, {multiFeatureIndex: 1});
// => Feature
// Last Segment of last Multi-Feature
turf.findPoint(multiLine, {multiFeatureIndex: -1, coordIndex: -1});
// => Feature
`
Returns [Feature][7]<[Point][26]> 2-vertex GeoJSON Feature Point
[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function
[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array
[3]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
[4]: #coordeachcallback
[5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean
[6]: #coordreducecallback
[7]: https://tools.ietf.org/html/rfc7946#section-3.2
[8]: https://tools.ietf.org/html/rfc7946#section-3.3
[9]: #propeachcallback
[10]: https://tools.ietf.org/html/rfc7946#section-3.1
[11]: #propreducecallback
[12]: https://tools.ietf.org/html/rfc7946#section-3.1.8
[13]: #featureeachcallback
[14]: #featurereducecallback
[15]: https://tools.ietf.org/html/rfc7946#section-5
[16]: #geomeachcallback
[17]: #geomreducecallback
[18]: #flatteneachcallback
[19]: #flattenreducecallback
[20]: https://tools.ietf.org/html/rfc7946#section-3.1.4
[21]: #segmenteachcallback
[22]: #segmentreducecallback
[23]: #lineeachcallback
[24]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
[25]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
[26]: https://tools.ietf.org/html/rfc7946#section-3.1.2
---
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.
Install this single module individually:
`sh`
$ npm install @turf/meta
Or install the all-encompassing @turf/turf module that includes all modules as functions:
`sh``
$ npm install @turf/turf