@turf/flatten

What is @turf/flatten?

@turf/flatten is a module in the Turf.js library that is used to flatten any GeoJSON object into a FeatureCollection. This is particularly useful when dealing with complex nested geometries and you need to simplify them into a flat structure.

What are @turf/flatten's main functionalities?

Flattening a MultiPolygon

This code demonstrates how to flatten a MultiPolygon into a FeatureCollection of Polygons. The input is a MultiPolygon, and the output is a FeatureCollection with each Polygon as a separate feature.

const turf = require('@turf/turf');
const multiPolygon = turf.multiPolygon([[[[0, 0], [10, 0], [10, 10], [0, 10], [0, 0]]], [[[20, 20], [30, 20], [30, 30], [20, 30], [20, 20]]]]);
const flattened = turf.flatten(multiPolygon);
console.log(flattened);

Flattening a MultiLineString

This code demonstrates how to flatten a MultiLineString into a FeatureCollection of LineStrings. The input is a MultiLineString, and the output is a FeatureCollection with each LineString as a separate feature.

const turf = require('@turf/turf');
const multiLineString = turf.multiLineString([[[0, 0], [10, 10]], [[20, 20], [30, 30]]]);
const flattened = turf.flatten(multiLineString);
console.log(flattened);

Flattening a GeometryCollection

This code demonstrates how to flatten a GeometryCollection into a FeatureCollection of individual geometries. The input is a GeometryCollection, and the output is a FeatureCollection with each geometry as a separate feature.

const turf = require('@turf/turf');
const geometryCollection = turf.geometryCollection([
  turf.point([0, 0]),
  turf.lineString([[10, 10], [20, 20]]),
  turf.polygon([[[30, 30], [40, 40], [50, 50], [30, 30]]])
]);
const flattened = turf.flatten(geometryCollection);
console.log(flattened);

Other packages similar to @turf/flatten

geojson-flatten

The geojson-flatten package provides similar functionality to @turf/flatten by flattening nested GeoJSON objects into simpler structures. It is a lightweight alternative but does not offer the extensive suite of geospatial analysis tools that Turf.js provides.

geojson-utils

The geojson-utils package offers various utilities for working with GeoJSON data, including flattening nested structures. While it provides some similar functionalities, it is more of a general-purpose toolkit for GeoJSON manipulation rather than a specialized library like Turf.js.

README

@turf/flatten

flatten

Flattens any GeoJSON to a FeatureCollection inspired by geojson-flatten.

Parameters

• geojson Feature any valid GeoJSON with multi-geometry Features

Examples

var geometry = {
  "type": "MultiPolygon",
  "coordinates": [
    [[[102.0, 2.0], [103.0, 2.0], [103.0, 3.0], [102.0, 3.0], [102.0, 2.0]]],
     [[[100.0, 0.0], [101.0, 0.0], [101.0, 1.0], [100.0, 1.0], [100.0, 0.0]],
     [[100.2, 0.2], [100.8, 0.2], [100.8, 0.8], [100.2, 0.8], [100.2, 0.2]]]
   ]
 };

var flattened = turf.flatten(geometry);

//=flattened

Returns FeatureCollection a flattened FeatureCollection

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/flatten

Or install the Turf module that includes it as a function:

$ npm install @turf/turf