Package Exports

@turf/meta

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Readme

@turf/meta

coordEachCallback

Callback for coordEach

Type: Function

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.

coordEach

Iterate over coordinates in any GeoJSON object, similar to Array.forEach()

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback 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) {
  //=currentCoord
  //=coordIndex
  //=featureIndex
  //=featureSubIndex
});

coordReduce

Reduce coordinates in any GeoJSON object, similar to Array.reduce()

Parameters

geojson (FeatureCollection | Geometry | Feature) any GeoJSON object
callback 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) {
  //=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.

Type: Function

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.

propEach

Iterate over properties in any GeoJSON object, similar to Array.forEach()

Parameters

geojson (FeatureCollection | Feature) any GeoJSON object
callback Function 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
});

propEachCallback

Callback for propEach

Type: Function

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.

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

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.

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 object
callback 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) {
  //=previousValue
  //=currentProperties
  //=featureIndex
  return currentProperties
});

Returns any The value that results from the reduction.

featureEachCallback

Callback for featureEach

Type: Function

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.

featureEach

Iterate over features in any GeoJSON object, similar to Array.forEach.

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback Function 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
});

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

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.

featureReduce

Reduce features in any GeoJSON object, similar to Array.reduce().

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback 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) {
  //=previousValue
  //=currentFeature
  //=featureIndex
  return currentFeature
});

Returns any The value that results from the reduction.

coordAll

Get all coordinates from any GeoJSON object.

Parameters

geojson (FeatureCollection | Feature | Geometry) 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

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.

geomEach

Iterate over each geometry in any GeoJSON object, similar to Array.forEach()

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback Function a method that takes (currentGeometry, featureIndex, currentProperties)

Examples

var features = turf.featureCollection([
    turf.point([26, 37], {foo: 'bar'}),
    turf.point([36, 53], {hello: 'world'})
]);

turf.geomEach(features, function (currentGeometry, featureIndex, currentProperties) {
  //=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.

Type: Function

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.

geomReduce

Reduce geometry in any GeoJSON object, similar to Array.reduce().

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback 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) {
  //=previousValue
  //=currentGeometry
  //=featureIndex
  //=currentProperties
  return currentGeometry
});

Returns any The value that results from the reduction.

flattenEachCallback

Callback for flattenEach

Type: Function

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.

flattenEach

Iterate over flattened features in any GeoJSON object, similar to Array.forEach.

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback Function a method that takes (currentFeature, featureIndex, featureSubIndex)

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) {
  //=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.

Type: Function

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.

flattenReduce

Reduce flattened features in any GeoJSON object, similar to Array.reduce().

Parameters

geojson (FeatureCollection | Feature | Geometry) any GeoJSON object
callback 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) {
  //=previousValue
  //=currentFeature
  //=featureIndex
  //=featureSubIndex
  return currentFeature
});

Returns any The value that results from the reduction.

segmentEachCallback

Callback for segmentEach

Type: Function

Parameters

currentSegment Feature<LineString> The current segment being processed.
featureIndex number The featureIndex currently being processed, starts at index 0.
featureSubIndex number The featureSubIndex currently being processed, starts at index 0.
segmentIndex number The segmentIndex currently being processed, starts at index 0.

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

geojson (FeatureCollection | Feature | Geometry) any GeoJSON
callback Function a method that takes (currentSegment, featureIndex, featureSubIndex)

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, featureSubIndex, segmentIndex) {
  //= currentSegment
  //= featureIndex
  //= featureSubIndex
  //= 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

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.
featureIndex number The featureIndex currently being processed, starts at index 0.
featureSubIndex number The featureSubIndex currently being processed, starts at index 0.
segmentIndex number The segmentIndex currently being processed, starts at index 0.

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 GeoJSON
callback 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]]]);

// Iterate over GeoJSON by 2-vertex segments
turf.segmentReduce(polygon, function (previousSegment, currentSegment, featureIndex, featureSubIndex, segmentIndex) {
  //= previousSegment
  //= currentSegment
  //= featureIndex
  //= featureSubIndex
  //= segmentInex
  return currentSegment
});

// Calculate the total number of segments
var initialValue = 0
var total = turf.segmentReduce(polygon, function (previousValue) {
    previousValue++;
    return previousValue;
}, initialValue);

Returns void

lineEachCallback

Callback for lineEach

Type: Function

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 0

lineEach

Iterate over line or ring coordinates in LineString, Polygon, MultiLineString, MultiPolygon Features or Geometries, similar to Array.forEach.

Parameters

geojson (Geometry | Feature<(LineString | Polygon | MultiLineString | MultiPolygon)>) object
callback Function a method that takes (currentLine, lineIndex, lineSubIndex)

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) {
  //=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.

Type: Function

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 0

lineReduce

Reduce features in any GeoJSON object, similar to Array.reduce().

Parameters

geojson (Geometry | Feature<(LineString | Polygon | MultiLineString | MultiPolygon)>) object
callback 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 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) {
  //=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