@turf/meta
Advanced tools
@turf/meta is a module of the Turf.js library that provides utility functions for working with GeoJSON data. It allows you to iterate over various GeoJSON objects, extract specific properties, and manipulate geometries.
coordEach
The `coordEach` function iterates over each coordinate in any GeoJSON object, allowing you to perform operations on each coordinate.
const turf = require('@turf/meta');
const point = { "type": "Feature", "geometry": { "type": "Point", "coordinates": [110, 50] } };
turf.coordEach(point, function (coord) {
console.log(coord);
});propEach
The `propEach` function iterates over properties in any GeoJSON Feature or FeatureCollection, allowing you to access and manipulate properties.
const turf = require('@turf/meta');
const featureCollection = { "type": "FeatureCollection", "features": [ { "type": "Feature", "properties": { "name": "A" }, "geometry": { "type": "Point", "coordinates": [110, 50] } } ] };
turf.propEach(featureCollection, function (properties, featureIndex) {
console.log(properties);
});geomEach
The `geomEach` function iterates over each geometry in any GeoJSON object, allowing you to perform operations on each geometry.
const turf = require('@turf/meta');
const featureCollection = { "type": "FeatureCollection", "features": [ { "type": "Feature", "geometry": { "type": "Point", "coordinates": [110, 50] } } ] };
turf.geomEach(featureCollection, function (geometry, featureIndex) {
console.log(geometry);
});The `geojson-utils` package provides utility functions for manipulating and analyzing GeoJSON data. It offers similar functionalities to @turf/meta, such as iterating over coordinates and geometries, but it also includes additional features like distance calculations and point-in-polygon tests.
The `geolib` package is a library for geospatial calculations. While it does not focus specifically on GeoJSON, it provides a wide range of geospatial utilities, including distance calculations, bounding box operations, and coordinate transformations. It can be used in conjunction with GeoJSON data for various geospatial tasks.
The `geojson-extent` package is designed to calculate the bounding box of GeoJSON objects. While it does not offer the same breadth of functionality as @turf/meta, it is useful for specific tasks related to determining the spatial extent of GeoJSON data.
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.geojsoncallbackexcludeWrapCoordIterate 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) {
//=currentCoord
//=coordIndex
//=featureIndex
//=featureSubIndex
});
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) {
//=previousValue
//=currentCoord
//=coordIndex
//=featureIndex
//=featureSubIndex
return currentCoord;
});
Returns Any The value that results from the reduction.
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:
If an initialValue is not provided:
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.geojsoncallbackinitialValueexcludeWrapCoordIterate over properties in any GeoJSON object, similar to Array.forEach()
Parameters
geojson (FeatureCollection | Feature) any GeoJSON objectcallback 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
});
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.geojsoncallbackReduce 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) {
//=previousValue
//=currentProperties
//=featureIndex
return currentProperties
});
Returns Any The value that results from the reduction.
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:
If an initialValue is not provided:
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.geojsoncallbackinitialValueIterate over features in any GeoJSON object, similar to Array.forEach.
Parameters
geojson (FeatureCollection | Feature | Geometry) any GeoJSON objectcallback 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
});
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.geojsoncallbackCallback 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:
If an initialValue is not provided:
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.geojsoncallbackinitialValueReduce 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) {
//=previousValue
//=currentFeature
//=featureIndex
return currentFeature
});
Returns Any The value that results from the reduction.
Get all coordinates from any GeoJSON object.
Parameters
geojson (FeatureCollection | Feature | Geometry) any GeoJSON objectExamples
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
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.geojsoncallbackIterate over each geometry in any GeoJSON object, similar to Array.forEach()
Parameters
geojson (FeatureCollection | Feature | Geometry) any GeoJSON objectcallback 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
});
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:
If an initialValue is not provided:
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.geojsoncallbackinitialValueReduce 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) {
//=previousValue
//=currentGeometry
//=featureIndex
//=currentProperties
return currentGeometry
});
Returns Any The value that results from the reduction.
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.geojsoncallbackIterate over flattened features in any GeoJSON object, similar to Array.forEach.
Parameters
geojson (FeatureCollection | Feature | Geometry) any GeoJSON objectcallback 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
});
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:
If an initialValue is not provided:
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.geojsoncallbackinitialValueReduce 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) {
//=previousValue
//=currentFeature
//=featureIndex
//=featureSubIndex
return currentFeature
});
Returns Any The value that results from the reduction.
Callback for segmentEach
Parameters
currentSegment Feature<LineString> The current segment being processed.featureIndex number The index of the current element being processed in the array, starts at index 0.featureSubIndex number The subindex of the current element being processed in the
array. Starts at index 0 and increases for each iterating line segment.geojsoncallbackReturns 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.
Parameters
geojson (FeatureCollection | Feature | Geometry) any GeoJSONcallback 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) {
//= currentSegment
//= featureIndex
//= featureSubIndex
});
// 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:
If an initialValue is not provided:
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.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.currentSubIndex [number] The subindex of the current element being processed in the
array. Starts at index 0 and increases for each iterating line segment.geojsoncallbackinitialValueReduce 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]]]);
// Iterate over GeoJSON by 2-vertex segments
turf.segmentReduce(polygon, function (previousSegment, currentSegment, currentIndex, currentSubIndex) {
//= previousSegment
//= currentSegment
//= currentIndex
//= currentSubIndex
return currentSegment
});
// Calculate the total number of segments
var initialValue = 0
var total = turf.segmentReduce(polygon, function (previousValue) {
previousValue++;
return previousValue;
}, initialValue);
Returns void
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 0geojsoncallbackIterate 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)>) objectcallback 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
});
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:
If an initialValue is not provided:
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 0geojsoncallbackinitialValueReduce features in any GeoJSON object, similar to Array.reduce().
Parameters
geojson (Geometry | Feature<(LineString | Polygon | MultiLineString | MultiPolygon)>) 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 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.
Install this module individually:
$ npm install @turf/meta
Or install the Turf module that includes it as a function:
$ npm install @turf/turf
FAQs
turf meta module
The npm package @turf/meta receives a total of 967,818 weekly downloads. As such, @turf/meta popularity was classified as popular.
We found that @turf/meta demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 9 open source maintainers collaborating on the project.
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