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EAH - Convert geohash decode code to typescript (#23955)
* Convert geohash decode code to typescript * Change decode geohash js file over to ts file * Update notice
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/* | ||
* Licensed to Elasticsearch B.V. under one or more contributor | ||
* license agreements. See the NOTICE file distributed with | ||
* this work for additional information regarding copyright | ||
* ownership. Elasticsearch B.V. licenses this file to you under | ||
* the Apache License, Version 2.0 (the "License"); you may | ||
* not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, | ||
* software distributed under the License is distributed on an | ||
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
* KIND, either express or implied. See the License for the | ||
* specific language governing permissions and limitations | ||
* under the License. | ||
*/ | ||
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interface Coordinates { | ||
latitude: number[]; | ||
longitude: number[]; | ||
} | ||
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export function decodeGeoHash(geohash: number[]): Coordinates { | ||
const BITS: number[] = [16, 8, 4, 2, 1]; | ||
const BASE32: string = '0123456789bcdefghjkmnpqrstuvwxyz'; | ||
let isEven: boolean = true; | ||
const lat: number[] = []; | ||
const lon: number[] = []; | ||
lat[0] = -90.0; | ||
lat[1] = 90.0; | ||
lon[0] = -180.0; | ||
lon[1] = 180.0; | ||
let latErr: number = 90.0; | ||
let lonErr: number = 180.0; | ||
for (const geohashEl of geohash) { | ||
const c: string = geohashEl.toString(); | ||
const cd: number = BASE32.indexOf(c); | ||
for (let j = 0; j < 5; j++) { | ||
const mask: number = BITS[j]; | ||
if (isEven) { | ||
lonErr = lonErr /= 2; | ||
refine_interval(lon, cd, mask); | ||
} else { | ||
latErr = latErr /= 2; | ||
refine_interval(lat, cd, mask); | ||
} | ||
isEven = !isEven; | ||
} | ||
} | ||
lat[2] = (lat[0] + lat[1]) / 2; | ||
lon[2] = (lon[0] + lon[1]) / 2; | ||
return { | ||
latitude: lat, | ||
longitude: lon, | ||
} as Coordinates; | ||
} | ||
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function refine_interval(interval: number[], cd: number, mask: number) { | ||
if (cd & mask) { /* tslint:disable-line */ | ||
interval[0] = (interval[0] + interval[1]) / 2; | ||
} else { | ||
interval[1] = (interval[0] + interval[1]) / 2; | ||
} | ||
} | ||
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/** | ||
* Get the number of geohash cells for a given precision | ||
* | ||
* @param {number} precision the geohash precision (1<=precision<=12). | ||
* @param {number} axis constant for the axis 0=lengthwise (ie. columns, along longitude), 1=heightwise (ie. rows, along latitude). | ||
* @returns {number} Number of geohash cells (rows or columns) at that precision | ||
*/ | ||
function geohashCells(precision: number, axis: number) { | ||
let cells = 1; | ||
for (let i = 1; i <= precision; i += 1) { | ||
/*On odd precisions, rows divide by 4 and columns by 8. Vice-versa on even precisions */ | ||
cells *= i % 2 === axis ? 4 : 8; | ||
} | ||
return cells; | ||
} | ||
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/** | ||
* Get the number of geohash columns (world-wide) for a given precision | ||
* @param precision the geohash precision | ||
* @returns {number} the number of columns | ||
*/ | ||
export function geohashColumns(precision: number): number { | ||
return geohashCells(precision, 0); | ||
} |