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geojson-index

geojson-index

Build Status Standard - JavaScript Style Guide

Create index a GeoJSON object's feature and for a query based on a GeoJSON object's feature. For creating an index only Point feature is supported. To cover simple, arbitrary areas the supported features are Point and Polygon.

This library uses S2, which means an index for a more specific position is longer and has the same prefix as a position that is bigger, but contains that area, so they are an ideal fit for database indices. Also S2 creates tiles and with these tiles it can cover areas, but these each tile has its own index, that's why the cover method returns an array of indices.

const geo = require('geojson-index')
 
const foo = {
  type: 'Feature',
  geometry: {
    type: 'Point',
    coordinates: [ 34.0908829, -118.3856206 ]
  },
  properties: { bar: 'baz' }
}
 
console.log('Index for this position:', geo.index(foo))
 
geo.cover({
  data: foo,
  radius: 100
}).then(ixs => {
  console.log('Indices for this query:', ixs)
}).catch(err => console.error(err))

install

$ npm i geojson-index

usage

geo.index(data)

Takes an Object, that is a proper GeoJSON object or GeoJSON feature that can be converted to one. Returns a String that is the index for this feature.

geo.cover(options[, callback])

options

  • data Object: a proper GeoJSON object or GeoJSON feature that can be converted to one
  • radius Number: the radius in meters, which the indices should cover.

Returns a Promise or calls a callback if specified with the result Array of index pairs. A pair is an object with a gte, and lt value, which means the indices in that area are greater than or equal to gte and lower than lt.

test

$ npm test