php LBS(附近地理位置)功能实现的一些思路

<?php/** * 查找两个经纬度之间的距离 * * @param ?$latitude1 ??float ?起始纬度 * @param ?$longitude1 ?float ?起始经度 * @param ?$latitude2 ??float ?目标纬度 * @param ?$longitude2 ?float ?目标经度 * @return array(miles=>英里,feet=>英尺,yards=>码,kilometers=>公里,meters=>米) * @example * * ????????$point1 = array(‘lat‘ => 40.770623, ‘long‘ => -73.964367); * ????????$point2 = array(‘lat‘ => 40.758224, ‘long‘ => -73.917404); * ????????$distance = getDistanceBetweenPointsNew($point1[‘lat‘], $point1[‘long‘], $point2[‘lat‘], $point2[‘long‘]); * ????????foreach ($distance as $unit => $value) { * ????????????echo $unit.‘: ‘.number_format($value,4); * ????????} * * ????????The example returns the following: * * ????????miles: 2.6025 ??????//英里 * ????????feet: 13,741.4350 ??//英尺 * ????????yards: 4,580.4783 ??//码 * ????????kilometers: 4.1884 ?//公里 * ????????meters: 4,188.3894 ?//米 * */function getDistanceBetweenPointsNew($latitude1, $longitude1, $latitude2, $longitude2) { ???$theta = $longitude1 - $longitude2; ???$miles = (sin(deg2rad($latitude1)) * sin(deg2rad($latitude2))) + (cos(deg2rad($latitude1)) * cos(deg2rad($latitude2)) * cos(deg2rad($theta))); ???$miles = acos($miles); ???$miles = rad2deg($miles); ???$miles = $miles * 60 * 1.1515; ???$feet = $miles * 5280; ???$yards = $feet / 3; ???$kilometers = $miles * 1.609344; ???$meters = $kilometers * 1000; ???return compact(‘miles‘, ‘feet‘, ‘yards‘, ‘kilometers‘, ‘meters‘);}?>

<?php/** * Encode and decode geohashes * */class Geohash { ???private $coding = "0123456789bcdefghjkmnpqrstuvwxyz"; ???private $codingMap = array(); ???public function Geohash() { ???????//build map from encoding char to 0 padded bitfield ???????for ($i = 0; $i < 32; $i++) { ???????????$this->codingMap[substr($this->coding, $i, 1)] = str_pad(decbin($i), 5, "0", STR_PAD_LEFT); ???????} ???} ???/** ????* Decode a geohash and return an array with decimal lat,long in it ????*/ ???public function decode($hash) { ???????//decode hash into binary string ???????$binary = ""; ???????$hl = strlen($hash); ???????for ($i = 0; $i < $hl; $i++) { ???????????$binary .= $this->codingMap[substr($hash, $i, 1)]; ???????} ???????//split the binary into lat and log binary strings ???????$bl = strlen($binary); ???????$blat = ""; ???????$blong = ""; ???????for ($i = 0; $i < $bl; $i++) { ???????????if ($i % 2) { ???????????????$blat = $blat . substr($binary, $i, 1); ???????????} else { ???????????????$blong = $blong . substr($binary, $i, 1); ???????????} ???????} ???????//now concert to decimal ???????$lat = $this->binDecode($blat, -90, 90); ???????$long = $this->binDecode($blong, -180, 180); ???????//figure out how precise the bit count makes this calculation ???????$latErr = $this->calcError(strlen($blat), -90, 90); ???????$longErr = $this->calcError(strlen($blong), -180, 180); ???????//how many decimal places should we use? There‘s a little art to ???????//this to ensure I get the same roundings as geohash.org ???????$latPlaces = max(1, -round(log10($latErr))) - 1; ???????$longPlaces = max(1, -round(log10($longErr))) - 1; ???????//round it ???????$lat = round($lat, $latPlaces); ???????$long = round($long, $longPlaces); ???????return array($lat, $long); ???} ???/** ????* Encode a hash from given lat and long ????*/ ???public function encode($lat, $long) { ???????//how many bits does latitude need? ???????$plat = $this->precision($lat); ???????$latbits = 1; ???????$err = 45; ???????while ($err > $plat) { ???????????$latbits++; ???????????$err /= 2; ???????} ???????//how many bits does longitude need? ???????$plong = $this->precision($long); ???????$longbits = 1; ???????$err = 90; ???????while ($err > $plong) { ???????????$longbits++; ???????????$err /= 2; ???????} ???????//bit counts need to be equal ???????$bits = max($latbits, $longbits); ???????//as the hash create bits in groups of 5, lets not ???????//waste any bits - lets bulk it up to a multiple of 5 ???????//and favour the longitude for any odd bits ???????$longbits = $bits; ???????$latbits = $bits; ???????$addlong = 1; ???????while (($longbits + $latbits) % 5 != 0) { ???????????$longbits += $addlong; ???????????$latbits += !$addlong; ???????????$addlong = !$addlong; ???????} ???????//encode each as binary string ???????$blat = $this->binEncode($lat, -90, 90, $latbits); ???????$blong = $this->binEncode($long, -180, 180, $longbits); ???????//merge lat and long together ???????$binary = ""; ???????$uselong = 1; ???????while (strlen($blat) + strlen($blong)) { ???????????if ($uselong) { ???????????????$binary = $binary . substr($blong, 0, 1); ???????????????$blong = substr($blong, 1); ???????????} else { ???????????????$binary = $binary . substr($blat, 0, 1); ???????????????$blat = substr($blat, 1); ???????????} ???????????$uselong = !$uselong; ???????} ???????//convert binary string to hash ???????$hash = ""; ???????for ($i = 0; $i < strlen($binary); $i += 5) { ???????????$n = bindec(substr($binary, $i, 5)); ???????????$hash = $hash . $this->coding[$n]; ???????} ???????return $hash; ???} ???/** ????* What‘s the maximum error for $bits bits covering a range $min to $max ????*/ ???private function calcError($bits, $min, $max) { ???????$err = ($max - $min) / 2; ???????while ($bits--) { ???????????$err /= 2; ???????} ???????return $err; ???} ???/* ????* returns precision of number ????* precision of 42 is 0.5 ????* precision of 42.4 is 0.05 ????* precision of 42.41 is 0.005 etc ????*/ ???private function precision($number) { ???????$precision = 0; ???????$pt = strpos($number, ‘.‘); ???????if ($pt !== false) { ???????????$precision = -(strlen($number) - $pt - 1); ???????} ???????return pow(10, $precision) / 2; ???} ???/** ????* create binary encoding of number as detailed in http://en.wikipedia.org/wiki/Geohash#Example ????* removing the tail recursion is left an exercise for the reader ????*/ ???private function binEncode($number, $min, $max, $bitcount) { ???????if ($bitcount == 0) { ???????????return ""; ???????} ???????#echo "$bitcount: $min $max<br>"; ???????//this is our mid point - we will produce a bit to say ???????//whether $number is above or below this mid point ???????$mid = ($min + $max) / 2; ???????if ($number > $mid) { ???????????return "1" . $this->binEncode($number, $mid, $max, $bitcount - 1); ???????} else { ???????????return "0" . $this->binEncode($number, $min, $mid, $bitcount - 1); ???????} ???} ???/** ????* decodes binary encoding of number as detailed in http://en.wikipedia.org/wiki/Geohash#Example ????* removing the tail recursion is left an exercise for the reader ????*/ ???private function binDecode($binary, $min, $max) { ???????$mid = ($min + $max) / 2; ???????if (strlen($binary) == 0) { ???????????return $mid; ???????} ???????$bit = substr($binary, 0, 1); ???????$binary = substr($binary, 1); ???????if ($bit == 1) { ???????????return $this->binDecode($binary, $mid, $max); ???????} else { ???????????return $this->binDecode($binary, $min, $mid); ???????} ???}}?>