@turf/meta
coordEachCallback
Callback for coordEach
Parameters
currentCoord
Array<number> The current coordinate being processed.coordIndex
number The current index of the coordinate being processed.
Starts at index 0.featureIndex
number The current index of the feature being processed.featureSubIndex
number The current subIndex of the feature being processed.geojson
callback
excludeWrapCoord
coordEach
Iterate over coordinates in any GeoJSON object, similar to Array.forEach()
Parameters
geojson
(FeatureCollection | Feature | Geometry) any GeoJSON objectcallback
Function a method that takes (currentCoord, coordIndex, featureIndex, featureSubIndex)excludeWrapCoord
[boolean] whether or not to include the final coordinate of LinearRings that wraps the ring in its iteration. (optional, default false
)
Examples
var features = turf.featureCollection([
turf.point([26, 37], {"foo": "bar"}),
turf.point([36, 53], {"hello": "world"})
]);
turf.coordEach(features, function (currentCoord, coordIndex, featureIndex, featureSubIndex) {
});
coordReduce
Reduce coordinates in any GeoJSON object, similar to Array.reduce()
Parameters
geojson
(FeatureCollection | Geometry | Feature) any GeoJSON objectcallback
Function a method that takes (previousValue, currentCoord, coordIndex)initialValue
[Any] Value to use as the first argument to the first call of the callback.excludeWrapCoord
[boolean] whether or not to include the final coordinate of LinearRings that wraps the ring in its iteration. (optional, default false
)
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, featureSubIndex) {
return currentCoord;
});
Returns Any The value that results from the reduction.
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.
Parameters
previousValue
Any The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentCoord
Array<number> The current coordinate being processed.coordIndex
number The current index of the coordinate being processed.
Starts at index 0, if an initialValue is provided, and at index 1 otherwise.featureIndex
number The current index of the feature being processed.featureSubIndex
number The current subIndex of the feature being processed.geojson
callback
initialValue
excludeWrapCoord
propEach
Iterate over properties in any GeoJSON object, similar to Array.forEach()
Parameters
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.propEach(features, function (currentProperties, featureIndex) {
});
propEachCallback
Callback for propEach
Parameters
currentProperties
Object The current properties being processed.featureIndex
number The index of the current element being processed in the
array.Starts at index 0, if an initialValue is provided, and at index 1 otherwise.geojson
callback
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) any GeoJSON objectcallback
Function a method that takes (previousValue, currentProperties, featureIndex)initialValue
[Any] 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) {
return currentProperties
});
Returns Any The value that results from the reduction.
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.
Parameters
previousValue
Any The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentProperties
Any The current properties being processed.featureIndex
number The index of the current element being processed in the
array.Starts at index 0, if an initialValue is provided, and at index 1 otherwise.geojson
callback
initialValue
featureEach
Iterate over features in any GeoJSON object, similar to
Array.forEach.
Parameters
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.featureEach(features, function (currentFeature, featureIndex) {
});
featureEachCallback
Callback for featureEach
Parameters
currentFeature
Feature<any> The current feature being processed.featureIndex
number The index of the current element being processed in the
array.Starts at index 0, if an initialValue is provided, and at index 1 otherwise.geojson
callback
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.
Parameters
previousValue
Any The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentFeature
Feature The current Feature being processed.featureIndex
number The index of the current element being processed in the
array.Starts at index 0, if an initialValue is provided, and at index 1 otherwise.geojson
callback
initialValue
featureReduce
Reduce features in any GeoJSON object, similar to Array.reduce().
Parameters
geojson
(FeatureCollection | Feature | Geometry) any GeoJSON objectcallback
Function a method that takes (previousValue, currentFeature, featureIndex)initialValue
[Any] 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) {
return currentFeature
});
Returns Any The value that results from the reduction.
coordAll
Get all coordinates from any GeoJSON object.
Parameters
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
var coords = turf.coordAll(features);
Returns Array<Array<number>> coordinate position array
geomEachCallback
Callback for geomEach
Parameters
currentGeometry
Geometry The current geometry being processed.currentIndex
number The index of the current element being processed in the
array. Starts at index 0, if an initialValue is provided, and at index 1 otherwise.currentProperties
number The current feature properties being processed.geojson
callback
geomEach
Iterate over each geometry in any GeoJSON object, similar to Array.forEach()
Parameters
Examples
var features = turf.featureCollection([
turf.point([26, 37], {foo: 'bar'}),
turf.point([36, 53], {hello: 'world'})
]);
turf.geomEach(features, function (currentGeometry, featureIndex, currentProperties) {
});
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.
Parameters
previousValue
Any The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentGeometry
Geometry The current Feature being processed.currentIndex
number The index of the current element being processed in the
array.Starts at index 0, if an initialValue is provided, and at index 1 otherwise.currentProperties
Object The current feature properties being processed.geojson
callback
initialValue
geomReduce
Reduce geometry in any GeoJSON object, similar to Array.reduce().
Parameters
geojson
(FeatureCollection | Feature | Geometry) any GeoJSON objectcallback
Function a method that takes (previousValue, currentGeometry, featureIndex, currentProperties)initialValue
[Any] 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, currentProperties) {
return currentGeometry
});
Returns Any The value that results from the reduction.
flattenEachCallback
Callback for flattenEach
Parameters
currentFeature
Feature The current flattened feature being processed.featureIndex
number The index of the current element being processed in the
array. Starts at index 0, if an initialValue is provided, and at index 1 otherwise.featureSubIndex
number The subindex of the current element being processed in the
array. Starts at index 0 and increases if the flattened feature was a multi-geometry.geojson
callback
flattenEach
Iterate over flattened features in any GeoJSON object, similar to
Array.forEach.
Parameters
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, featureSubIndex) {
});
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.
Parameters
previousValue
Any The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentFeature
Feature The current Feature being processed.featureIndex
number The index of the current element being processed in the
array.Starts at index 0, if an initialValue is provided, and at index 1 otherwise.featureSubIndex
number The subindex of the current element being processed in the
array. Starts at index 0 and increases if the flattened feature was a multi-geometry.geojson
callback
initialValue
flattenReduce
Reduce flattened features in any GeoJSON object, similar to Array.reduce().
Parameters
geojson
(FeatureCollection | Feature | Geometry) any GeoJSON objectcallback
Function a method that takes (previousValue, currentFeature, featureIndex, featureSubIndex)initialValue
[Any] 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, featureSubIndex) {
return currentFeature
});
Returns Any The value that results from the reduction.
segmentEachCallback
Callback for segmentEach
Parameters
currentSegment
Feature<LineString> The current segment being processed.segmentIndex
number The segmentIndex currently being processed, starts at index 0.featureIndex
number The featureIndex currently being processed, starts at index 0.featureSubIndex
number The featureSubIndex currently being processed, starts at index 0.geojson
callback
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
Examples
var polygon = turf.polygon([[[-50, 5], [-40, -10], [-50, -10], [-40, 5], [-50, 5]]]);
turf.segmentEach(polygon, function (currentSegment, featureIndex, featureSubIndex) {
});
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.
Parameters
previousValue
[Any] The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentSegment
[Feature<LineString>] The current segment being processed.segmentIndex
number The segmentIndex currently being processed, starts at index 0.featureIndex
number The featureIndex currently being processed, starts at index 0.featureSubIndex
number The featureSubIndex currently being processed, starts at index 0.geojson
callback
initialValue
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 GeoJSONcallback
Function a method that takes (previousValue, currentSegment, currentIndex)initialValue
[Any] 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]]]);
turf.segmentReduce(polygon, function (previousSegment, currentSegment, segmentIndex, featureIndex, featureSubIndex) {
return currentSegment
});
var initialValue = 0
var total = turf.segmentReduce(polygon, function (previousValue) {
previousValue++;
return previousValue;
}, initialValue);
Returns void
lineEachCallback
Callback for lineEach
Parameters
currentLine
Feature<LineString> The current LineString|LinearRing being processed.lineIndex
number The index of the current element being processed in the array, starts at index 0.lineSubIndex
number The sub-index of the current line being processed at index 0geojson
callback
lineEach
Iterate over line or ring coordinates in LineString, Polygon, MultiLineString, MultiPolygon Features or Geometries,
similar to Array.forEach.
Parameters
Examples
var mtLn = turf.multiLineString([
turf.lineString([[26, 37], [35, 45]]),
turf.lineString([[36, 53], [38, 50], [41, 55]])
]);
turf.lineEach(mtLn, function (currentLine, lineIndex) {
});
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.
Parameters
previousValue
Any The accumulated value previously returned in the last invocation
of the callback, or initialValue, if supplied.currentLine
Feature<LineString> The current LineString|LinearRing being processed.lineIndex
number The index of the current element being processed in the
array. Starts at index 0, if an initialValue is provided, and at index 1 otherwise.lineSubIndex
number The sub-index of the current line being processed at index 0geojson
callback
initialValue
lineReduce
Reduce features in any GeoJSON object, similar to Array.reduce().
Parameters
Examples
var mtp = 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(mtp, function (previousValue, currentLine, lineIndex, lineSubIndex) {
return currentLine
}, 2);
Returns Any The value that results from the reduction.
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/meta
Or install the Turf module that includes it as a function:
$ npm install @turf/turf