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radar-wp-custom/vendor/phayes/geophp/lib/adapters/GeoHash.class.php

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2015-02-24 16:25:12 +01:00
<?php
/**
* PHP Geometry GeoHash encoder/decoder.
*
* @author prinsmc
* @see http://en.wikipedia.org/wiki/Geohash
*
*/
class GeoHash extends GeoAdapter{
/**
* base32 encoding character map.
*/
private $table = "0123456789bcdefghjkmnpqrstuvwxyz";
/**
* array of neighbouring hash character maps.
*/
private $neighbours = array (
// north
'top' => array (
'even' => 'p0r21436x8zb9dcf5h7kjnmqesgutwvy',
'odd' => 'bc01fg45238967deuvhjyznpkmstqrwx'
),
// east
'right' => array (
'even' => 'bc01fg45238967deuvhjyznpkmstqrwx',
'odd' => 'p0r21436x8zb9dcf5h7kjnmqesgutwvy'
),
// west
'left' => array (
'even' => '238967debc01fg45kmstqrwxuvhjyznp',
'odd' => '14365h7k9dcfesgujnmqp0r2twvyx8zb'
),
// south
'bottom' => array (
'even' => '14365h7k9dcfesgujnmqp0r2twvyx8zb',
'odd' => '238967debc01fg45kmstqrwxuvhjyznp'
)
);
/**
* array of bordering hash character maps.
*/
private $borders = array (
// north
'top' => array (
'even' => 'prxz',
'odd' => 'bcfguvyz'
),
// east
'right' => array (
'even' => 'bcfguvyz',
'odd' => 'prxz'
),
// west
'left' => array (
'even' => '0145hjnp',
'odd' => '028b'
),
// south
'bottom' => array (
'even' => '028b',
'odd' => '0145hjnp'
)
);
/**
* Convert the geohash to a Point. The point is 2-dimensional.
* @return Point the converted geohash
* @param string $hash a geohash
* @see GeoAdapter::read()
*/
public function read($hash, $as_grid = FALSE) {
$ll = $this->decode($hash);
if (!$as_grid) {
return new Point($ll['medlon'], $ll['medlat']);
}
else {
return new Polygon(array(
new LineString(array(
new Point($ll['minlon'], $ll['maxlat']),
new Point($ll['maxlon'], $ll['maxlat']),
new Point($ll['maxlon'], $ll['minlat']),
new Point($ll['minlon'], $ll['minlat']),
new Point($ll['minlon'], $ll['maxlat']),
))
));
}
}
/**
* Convert the geometry to geohash.
* @return string the geohash or null when the $geometry is not a Point
* @param Point $geometry
* @see GeoAdapter::write()
*/
public function write(Geometry $geometry, $precision = NULL){
if ($geometry->isEmpty()) return '';
if($geometry->geometryType() === 'Point'){
return $this->encodePoint($geometry, $precision);
}
else {
// The geohash is the hash grid ID that fits the envelope
$envelope = $geometry->envelope();
$geohashes = array();
$geohash = '';
foreach ($envelope->getPoints() as $point) {
$geohashes[] = $this->encodePoint($point, 0.0000001);
}
$i = 0;
while ($i < strlen($geohashes[0])) {
$char = $geohashes[0][$i];
foreach ($geohashes as $hash) {
if ($hash[$i] != $char) {
return $geohash;
}
}
$geohash .= $char;
$i++;
}
return $geohash;
}
}
/**
* @return string geohash
* @param Point $point
* @author algorithm based on code by Alexander Songe <a@songe.me>
* @see https://github.com/asonge/php-geohash/issues/1
*/
private function encodePoint($point, $precision = NULL){
if ($precision === NULL) {
$lap = strlen($point->y())-strpos($point->y(),".");
$lop = strlen($point->x())-strpos($point->x(),".");
$precision = pow(10,-max($lap-1,$lop-1,0))/2;
}
$minlat = -90;
$maxlat = 90;
$minlon = -180;
$maxlon = 180;
$latE = 90;
$lonE = 180;
$i = 0;
$error = 180;
$hash='';
while($error>=$precision) {
$chr = 0;
for($b=4;$b>=0;--$b) {
if((1&$b) == (1&$i)) {
// even char, even bit OR odd char, odd bit...a lon
$next = ($minlon+$maxlon)/2;
if($point->x()>$next) {
$chr |= pow(2,$b);
$minlon = $next;
} else {
$maxlon = $next;
}
$lonE /= 2;
} else {
// odd char, even bit OR even char, odd bit...a lat
$next = ($minlat+$maxlat)/2;
if($point->y()>$next) {
$chr |= pow(2,$b);
$minlat = $next;
} else {
$maxlat = $next;
}
$latE /= 2;
}
}
$hash .= $this->table[$chr];
$i++;
$error = min($latE,$lonE);
}
return $hash;
}
/**
* @param string $hash a geohash
* @author algorithm based on code by Alexander Songe <a@songe.me>
* @see https://github.com/asonge/php-geohash/issues/1
*/
private function decode($hash){
$ll = array();
$minlat = -90;
$maxlat = 90;
$minlon = -180;
$maxlon = 180;
$latE = 90;
$lonE = 180;
for($i=0,$c=strlen($hash);$i<$c;$i++) {
$v = strpos($this->table,$hash[$i]);
if(1&$i) {
if(16&$v)$minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
if(8&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
if(4&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
if(2&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
if(1&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
$latE /= 8;
$lonE /= 4;
} else {
if(16&$v)$minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
if(8&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
if(4&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
if(2&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
if(1&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
$latE /= 4;
$lonE /= 8;
}
}
$ll['minlat'] = $minlat;
$ll['minlon'] = $minlon;
$ll['maxlat'] = $maxlat;
$ll['maxlon'] = $maxlon;
$ll['medlat'] = round(($minlat+$maxlat)/2, max(1, -round(log10($latE)))-1);
$ll['medlon'] = round(($minlon+$maxlon)/2, max(1, -round(log10($lonE)))-1);
return $ll;
}
/**
* Calculates the adjacent geohash of the geohash in the specified direction.
* This algorithm is available in various ports that seem to point back to
* geohash-js by David Troy under MIT notice.
*
*
* @see https://github.com/davetroy/geohash-js
* @see https://github.com/lyokato/objc-geohash
* @see https://github.com/lyokato/libgeohash
* @see https://github.com/masuidrive/pr_geohash
* @see https://github.com/sunng87/node-geohash
* @see https://github.com/davidmoten/geo
*
* @param string $hash the geohash (lowercase)
* @param string $direction the direction of the neighbor (top, bottom, left or right)
* @return string the geohash of the adjacent cell
*/
public function adjacent($hash, $direction){
$last = substr($hash, -1);
$type = (strlen($hash) % 2)? 'odd': 'even';
$base = substr($hash, 0, strlen($hash) - 1);
if(strpos(($this->borders[$direction][$type]), $last) !== false){
$base = $this->adjacent($base, $direction);
}
return $base.$this->table[strpos($this->neighbours[$direction][$type], $last)];
}
}