Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | 1x 26x 26x 26x 26x 14x 12x 12x 12x 1x | /** ****************************************************************************************************
* File: decode.js
* Project: geohash
* @author Nick Soggin <iSkore@users.noreply.github.com> on 19-Feb-2019
*******************************************************************************************************/
'use strict';
const
geohashToBBox = require( './geohashToBBox' );
/**
* decode
* Decode geohash to latitude/longitude (location is approximate centre of geohash cell, to reasonable precision).
* Will round to close to centre without excessive precision: ⌊2-log10(Δ°)⌋ decimal places.
*
* @param {string} geohash - Geohash string to be converted to latitude/longitude.
* @param {boolean} [calculateErrorOffset=false] - calculate the natural amount of geospatial inaccuracy
* @returns {{lng,lat}|{lng,lat,error:{lng,lat}}} - Center of geohashed location.
* @throws Invalid geohash.
*
* @example
* const latlng = decode( 'dqbvhgk' ); // latlng: { lng: -77.4804, lat: 38.8662 }
*/
function decode( geohash, calculateErrorOffset = false ) {
const
bbox = geohashToBBox( geohash );
let
lng = ( bbox[ 0 ] + bbox[ 2 ] ) / 2,
lat = ( bbox[ 1 ] + bbox[ 3 ] ) / 2;
if ( calculateErrorOffset ) {
return {
lng, lat,
error: {
lng: bbox[ 2 ] - lng,
lat: bbox[ 3 ] - lat
}
};
}
else {
// round to close to centre without excessive precision: ⌊2-log10(Δ°)⌋ decimal places
lng = +lng.toFixed( ~~( 2 - Math.log( bbox[ 2 ] - bbox[ 0 ] ) / Math.LN10 ) );
lat = +lat.toFixed( ~~( 2 - Math.log( bbox[ 3 ] - bbox[ 1 ] ) / Math.LN10 ) );
return { lng, lat };
}
}
module.exports = decode;
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