geojson-equality

What is geojson-equality?

The geojson-equality npm package is used to compare GeoJSON objects for structural equality. It helps in determining if two GeoJSON objects represent the same geometry, even if their coordinates are ordered differently or if they have different properties.

What are geojson-equality's main functionalities?

Compare GeoJSON objects for equality

This feature allows you to compare two GeoJSON objects to check if they are equal. The comparison takes into account the structure and coordinates of the GeoJSON objects.

const GeojsonEquality = require('geojson-equality');
const equality = new GeojsonEquality();

const geojson1 = { "type": "Point", "coordinates": [100.0, 0.0] };
const geojson2 = { "type": "Point", "coordinates": [100.0, 0.0] };

console.log(equality.compare(geojson1, geojson2)); // true

Compare GeoJSON objects with tolerance

This feature allows you to compare two GeoJSON objects with a specified precision tolerance. This is useful when dealing with floating-point inaccuracies.

const GeojsonEquality = require('geojson-equality');
const equality = new GeojsonEquality({ precision: 6 });

const geojson1 = { "type": "Point", "coordinates": [100.000001, 0.000001] };
const geojson2 = { "type": "Point", "coordinates": [100.0, 0.0] };

console.log(equality.compare(geojson1, geojson2)); // true

Compare GeoJSON objects ignoring properties

This feature allows you to compare two GeoJSON objects while ignoring their properties. This is useful when you only care about the geometry and not the associated properties.

const GeojsonEquality = require('geojson-equality');
const equality = new GeojsonEquality({ ignoreProperties: true });

const geojson1 = { "type": "Point", "coordinates": [100.0, 0.0], "properties": { "name": "A" } };
const geojson2 = { "type": "Point", "coordinates": [100.0, 0.0], "properties": { "name": "B" } };

console.log(equality.compare(geojson1, geojson2)); // true

Other packages similar to geojson-equality

turf

Turf is a powerful geospatial analysis library that includes a wide range of functions for processing GeoJSON data. It offers more comprehensive geospatial analysis capabilities compared to geojson-equality, including measurement, transformation, and data manipulation functions.

deep-equal

Deep-equal is a general-purpose deep comparison library that can be used to compare any JavaScript objects, including GeoJSON objects. While it does not offer GeoJSON-specific features like geojson-equality, it is versatile and can be used for a wide range of deep comparison tasks.

geojson-utils

Geojson-utils is a library that provides utility functions for working with GeoJSON data. It includes functions for distance calculation, point-in-polygon tests, and bounding box calculations. While it does not focus on equality comparison, it offers a variety of tools for GeoJSON data manipulation.

README

geojson-equality

Check two valid geojson geometries for equality.

installation

npm install geojson-equality

usage

var GeojsonEquality = require('geojson-equality');
var eq = new GeojsonEquality();
 
var g1 = { "type": "Polygon", "coordinates": [
  [[30, 10], [40, 40], [20, 40], [10, 20], [30, 10]]
]};
var g2 = { "type": "Polygon", "coordinates": [
  [[30, 10], [40, 40], [20, 40], [10, 20], [30, 10]]
]};

eq.compare(g1,g2);    // returns true
var g3 = { "type": "Polygon", "coordinates": [
  [[300, 100], [400, 400], [200, 400], [100, 200], [300, 100]]
]};

eq.compare(g1,g3);    // returns false

For including in browser, download file geojson-equality.min.js

<script type="text/javascipt" src="path/to/geojson-equality.min.js"></script>

This create a global variable 'GeojsonEquality' GeojsonEquality class can be initiated with many options that are used to match the geojson.

• precision number as floating points precision required. Defualt is 17

var g1 = { "type": "Point", "coordinates": [30.2, 10] };
var g2 = { "type": "Point", "coordinates": [30.22233, 10] };
var eq = new GeojsonEquality({precision: 3});
eq.compare(g1,g2);  // returns false
var eq = new GeojsonEquality({precision: 1});
eq.compare(g1,g2);  // returns true

• direction true | false, direction of LineString or Polygon (orientation) is ignored if false. Default is false.

  var g1 = { "type": "LineString", "coordinates": 
    [ [30, 10], [10, 30], [40, 40] ] };
  var g2 = { "type": "LineString", "coordinates": 
    [ [40, 40], [10, 30], [30, 10] ] };
  var eq = new GeojsonEquality({direction: false});
  eq.compare(g1,g2);  // returns true
  var eq = new GeojsonEquality({direction: true});
  eq.compare(g1,g2);  // returns false

• objectComparator function, custom function for use in comparing Feature properties. Default is a shallow comparison.

  // using lodash isEqual to deep comparison
  var isEqual = require('lodash/lang/isEqual')
  var eq = new GeojsonEquality({objectComparator: isEqual});

developing

Once you run

npm install

then for running test

npm run test

to create build

npm run build

license

This project is licensed under the terms of the MIT license.