Created
March 21, 2013 22:29
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Testing GeoHash library
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| <?php | |
| class GeoHash { | |
| private $hash; | |
| private $latitude; | |
| private $longitude; | |
| private $precision; | |
| /** | |
| * Returns the hash | |
| * @return string | |
| */ | |
| public function getHash() { | |
| if(!$this->hash) { | |
| if(empty($this->latitude)) throw new Exception("Latitude is required"); | |
| if(empty($this->longitude)) throw new Exception("Longitude is required"); | |
| $this->hash = $this->createHash(); | |
| } | |
| return $this->hash; | |
| } | |
| /** | |
| * Set a hash, this will clear any latitude/longitude or precision set | |
| * @return GeoHash | |
| */ | |
| public function setHash($hash) { | |
| $this->hash = $hash; | |
| $this->parseHash(); | |
| return $this; | |
| } | |
| /** | |
| * Get the latitude | |
| * @return float | |
| */ | |
| public function getLatitude() { | |
| return $this->latitude; | |
| } | |
| /** | |
| * Set a latitude, this will clear any hash | |
| * @return GeoHash | |
| */ | |
| public function setLatitude($latitude) { | |
| $this->hash = null; | |
| $this->latitude = $latitude; | |
| return $this; | |
| } | |
| /** | |
| * Get the longitude | |
| * @return float | |
| */ | |
| public function getLongitude() { | |
| return $this->longitude; | |
| } | |
| /** | |
| * Set a latitude, this will clear any hash | |
| * @return GeoHash | |
| */ | |
| public function setLongitude($longitude) { | |
| $this->hash = null; | |
| $this->longitude = $longitude; | |
| return $this; | |
| } | |
| /** | |
| * Gets the precision | |
| * @return float | |
| */ | |
| public function getPrecision() { | |
| return $this->precision; | |
| } | |
| /** | |
| * Set a precision, clears any hash | |
| * @return GeoHash | |
| */ | |
| public function setPrecision($precision) { | |
| $this->hash = null; | |
| $this->precision = $precision; | |
| return $this; | |
| } | |
| /** | |
| * Return the hash, obviously, to print out | |
| * @return string | |
| */ | |
| public function __toString() { | |
| return $this->getHash(); | |
| } | |
| private function clearCoords() { | |
| $this->latitude = null; | |
| $this->longitude = null; | |
| $this->precision = null; | |
| } | |
| private function createHash() { | |
| $table = "0123456789bcdefghjkmnpqrstuvwxyz"; | |
| $lng = $this->longitude; | |
| $lat = $this->latitude; | |
| if(isset($this->precision)) { | |
| $p = $this->precision; | |
| } else { | |
| $lap = strlen($lat)-strpos($lat,"."); | |
| $lop = strlen($lng)-strpos($lng,"."); | |
| $p = $this->precision = pow(10,-max($lap-1,$lop-1,0))/2; | |
| } | |
| $minlat = -90; | |
| $maxlat = 90; | |
| $minlng = -180; | |
| $maxlng = 180; | |
| $latE = 90; | |
| $lngE = 180; | |
| $i=0; | |
| $hash = ""; | |
| $error = 180; | |
| while($error>=$p) { | |
| $chr = 0; | |
| for($b=4;$b>=0;--$b) { | |
| if((1&$b) == (1&$i)) { // even char, even bit OR odd char, odd bit...a lng | |
| $next = ($minlng+$maxlng)/2; | |
| if($lng>$next) { | |
| $chr |= pow(2,$b); | |
| $minlng = $next; | |
| } else { | |
| $maxlng = $next; | |
| } | |
| $lngE /= 2; | |
| } else { // odd char, even bit OR even char, odd bit...a lat | |
| $next = ($minlat+$maxlat)/2; | |
| if($lat>$next) { | |
| $chr |= pow(2,$b); | |
| $minlat = $next; | |
| } else { | |
| $maxlat = $next; | |
| } | |
| $latE /= 2; | |
| } | |
| } | |
| $hash .= $table[$chr]; | |
| $i++; | |
| $error = min($latE,$lngE); | |
| } | |
| return $hash; | |
| } | |
| private function parseHash() { | |
| $table = "0123456789bcdefghjkmnpqrstuvwxyz"; | |
| $hash = $this->hash; | |
| $this->clearCoords(); | |
| $minlat = -90; | |
| $maxlat = 90; | |
| $minlng = -180; | |
| $maxlng = 180; | |
| $latE = 90; | |
| $lngE = 180; | |
| for($i=0,$c=strlen($hash);$i<$c;$i++) { | |
| $v = strpos($table,$hash[$i]); | |
| if(1&$i) { | |
| if(16&$v)$minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2; | |
| if(8&$v) $minlng = ($minlng+$maxlng)/2; else $maxlng = ($minlng+$maxlng)/2; | |
| if(4&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2; | |
| if(2&$v) $minlng = ($minlng+$maxlng)/2; else $maxlng = ($minlng+$maxlng)/2; | |
| if(1&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2; | |
| $latE /= 8; | |
| $lngE /= 4; | |
| } else { | |
| if(16&$v)$minlng = ($minlng+$maxlng)/2; else $maxlng = ($minlng+$maxlng)/2; | |
| if(8&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2; | |
| if(4&$v) $minlng = ($minlng+$maxlng)/2; else $maxlng = ($minlng+$maxlng)/2; | |
| if(2&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2; | |
| if(1&$v) $minlng = ($minlng+$maxlng)/2; else $maxlng = ($minlng+$maxlng)/2; | |
| $latE /= 4; | |
| $lngE /= 8; | |
| } | |
| } | |
| $this->latitude = round(($minlat+$maxlat)/2, max(1, -round(log10($latE)))-1); | |
| $this->longitude = round(($minlng+$maxlng)/2, max(1, -round(log10($lngE)))-1); | |
| $this->precision = max($latE,$lngE); | |
| } | |
| } | |
| //---------------------------------------- | |
| ////////////// | |
| // Test | |
| ////////////// | |
| $inputLat = 26.8745; | |
| $inputLon = -118.307; | |
| $geohash = new GeoHash; | |
| $geohash->setLatitude($inputLat)->setLongitude($inputLon)->setPrecision(pow(.1, 15)); | |
| $baseConverted = base_convert($geohash->getHash(), 32, 10); | |
| $convertBack = new GeoHash; | |
| $convertBack->setHash(base_convert($baseConverted, 10, 32)); | |
| var_dump($convertBack); | |
| /* | |
| object(GeoHash)[5] | |
| private 'hash' => string '9kgbgu77r1i0000000' (length=18) | |
| private 'latitude' => float 26.8744951487 | |
| private 'longitude' => float -118.307003975 | |
| private 'precision' => float 5.11590769747E-12 | |
| */ |
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