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December 4, 2015 15:16
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Geosyl.js – Convert Latitude longitude Pairs to Readable Words
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| // Geosyl.js – Convert Latitude longitude Pairs to Readable Words. | |
| // based on David Troy's https://github.com/davetroy/hash-js | |
| // also see: http://www.movable-type.co.uk/scripts/hash.html | |
| // Distributed under the MIT License | |
| geosyl = (function(){ | |
| var bits = [32, 16, 8, 4, 2, 1], | |
| vocals = 'aeiou'.split(''), | |
| consonants = 'kgsztdnhfpmyr'.split(''), | |
| syllables = []; | |
| vocals.forEach(function(vocal){ | |
| consonants.forEach(function(consonant) { | |
| syllables.push(consonant + vocal); | |
| }); | |
| }); | |
| function refine_interval(interval, cd, mask) { | |
| var mid = (interval[0] + interval[1]) / 2; | |
| interval[cd & mask ? 0 : 1] = mid; | |
| } | |
| return { | |
| decode: function (hash) { | |
| hash = hash | |
| .replace(/\W/g, '') | |
| .toLowerCase() | |
| .match(/\w{2}/g); | |
| var isEven = 1, | |
| lat = [-90, 90], | |
| lng = [-180, 180], | |
| mask, | |
| part, | |
| i; | |
| for (i = 0; i < hash.length; i++) { | |
| part = hash[i]; | |
| index = syllables.indexOf(part); | |
| for (j = 0; j < bits.length; j++) { | |
| mask = bits[j]; | |
| if (isEven) { | |
| refine_interval(lng, index, mask); | |
| } else { | |
| refine_interval(lat, index, mask); | |
| } | |
| isEven = !isEven; | |
| } | |
| } | |
| return [lat[0], lng[0], lat[1], lng[1]]; | |
| }, | |
| encode: function(latitude, longitude, precision) { | |
| var isEven = true, | |
| lat = [-90, 90], | |
| lng = [-180, 180], | |
| bit = 0, | |
| index = 0, | |
| hash = [], | |
| mid; | |
| precision = precision || 9; | |
| while (hash.length < precision) { | |
| if (isEven) { | |
| mid = (lng[0] + lng[1]) / 2; | |
| if (longitude > mid) { | |
| index |= bits[bit]; | |
| lng[0] = mid; | |
| } else | |
| lng[1] = mid; | |
| } else { | |
| mid = (lat[0] + lat[1]) / 2; | |
| if (latitude > mid) { | |
| index |= bits[bit]; | |
| lat[0] = mid; | |
| } else | |
| lat[1] = mid; | |
| } | |
| isEven = !isEven; | |
| if (bit < bits.length-1) { | |
| bit++; | |
| } else { | |
| hash.push(syllables[index]); | |
| bit = 0; | |
| index = 0; | |
| } | |
| } | |
| return hash.map(function(syllable, index) { | |
| return syllable + (( | |
| index % 3 == 2 && | |
| index < hash.length - 1 | |
| ) ? ' ' : ''); | |
| }).join(''); | |
| } | |
| } | |
| })(); | |
| var lat = 51.5, | |
| lng = 10, | |
| hash = geosyl.encode(lat, lng), | |
| bounds = geosyl.decode(hash); | |
| console.log(lat, lng); | |
| console.log(hash); | |
| console.log(bounds); | |
| console.log(Math.abs(bounds[0] - lat)) | |
| console.log(Math.abs(bounds[1] - lng)) |
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