php - Search or sort multi dimensional array for closest lat and lon values

Solution:

The Function here would do just that.... however, it returns a Multidimensional Array with with 2 major Elementslatitudes andlongitudes. The longitudes hold all the sorted Entries for the closest longitude values and the "latitudes" as well hold the sorted Entries for the closest latitude values. By default, the Function only returns the very Closest Match latitudinally and longitudinally. However, passing false as the last Parameter returns all sorted entries. The Code below illustrates it all:

<?php
    $arrGeoData = array(
        array(
            "zipcode"   => 28299,
            "latitude"  => 36.234982,
            "longitude" => -81.913799,
            "cityname"  => "ACME",
        ),
        array(
            "zipcode"   => 17198,
            "latitude"  => 50.735880,
            "longitude" => -74.143855,
            "cityname"  => "NEWLAND",
        ),
        array(
            "zipcode"   => 12203,
            "latitude"  => 41.711931,
            "longitude" => -75.011806,
            "cityname"  => "ACE",
        ),
    );
    $nearestLongLat     = sortByNearestLatLong($arrGeoData, 50.6000, -74.15000);
    var_dump(nearestLongLat);

    function sortByNearestLatLong($geoData, $lat, $long, $returnNearestOnly=true){
        // CREATE AN ARRAY FOR USE INSIDE THE FUNCTION
        $arrCloseMatchLat   = array();
        $arrCloseMatchLong  = array();
        $matchedGeoSet      = array();

        // LOOP THROUGH ALL THE $geoData ARRAY AND SUBTRACT THE GIVEN LAT & LONG VALUES
        // FROM THOSE CONTAINED IN THE ORIGINAL ARRAY: $geoData
        // WE KNOW THAT THE SMALLER THE RESULT OF THE SUBTRACTION; THE CLOSER WE ARE
        // WE DO THIS FOR BOTH THE LONGITUDE & LATITUDE... HENCE OUR ARRAY:
        // $arrCloseMatchLat AND $arrCloseMatchLong RESPECTIVELY
        foreach($geoData as $iKey=>$arrGeoStrip){
            $arrCloseMatchLat[$iKey]    =  abs(floatval( ($arrGeoStrip['latitude'])  - $lat  ));
            $arrCloseMatchLong[$iKey]   =  abs(floatval( ($arrGeoStrip['longitude']) - $long ));
        }


    // WE SORT BOTH ARRAYS NUMERICALLY KEEPING THE KEYS WHICH WE NEED FOR OUR FINAL RESULT
        asort($arrCloseMatchLat, SORT_NUMERIC);
        asort($arrCloseMatchLong, SORT_NUMERIC);

        // WE CAN RETURN ONLY THE RESULT OF THE FIRST, CLOSEST MATCH
        if($returnNearestOnly){
            foreach($arrCloseMatchLat as $index=>$difference){
                $matchedGeoSet['latitudes'][]  = $geoData[$index];
                break;
            }
            foreach($arrCloseMatchLong as $index=>$difference){
                $matchedGeoSet['longitudes'][] = $geoData[$index];
                break;
            }
            // OR WE CAN RETURN THE ENTIRE $geoData ARRAY ONLY SORTED IN A "CLOSEST FIRST" FASHION...
            // WE DO THIS FOR BOTH THE LONGITUDE & LATITUDE RESPECTIVELY SO WE END UP HAVING 2
            // ARRAYS: ONE THAT SORTS THE CLOSEST IN TERMS OF LONG VALUES
            // AN ONE THAT SORTS THE CLOSEST IN TERMS OF LAT VALUES...
        }else{
            foreach($arrCloseMatchLat as $index=>$difference){
                $matchedGeoSet['latitudes'][]  = $geoData[$index];
            }
            foreach($arrCloseMatchLong as $index=>$difference){
                $matchedGeoSet['longitudes'][] = $geoData[$index];
            }
        }
        return $matchedGeoSet;
    }
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The lines: $nearestLongLat = sortByNearestLatLong($arrGeoData, 50.6000, -74.15000); var_dump(nearestLongLat); above produces something like below. Notice the latitudes and longitudes keys

    array (size=2)
      'latitudes' => 
        array (size=1)
          0 => 
            array (size=4)
              'zipcode' => int 17198
              'latitude' => float 50.73588
              'longitude' => float -74.143855
              'cityname' => string 'NEWLAND' (length=7)
      'longitudes' => 
        array (size=1)
          0 => 
            array (size=4)
              'zipcode' => int 17198
              'latitude' => float 50.73588
              'longitude' => float -74.143855
              'cityname' => string 'NEWLAND' (length=7)
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Now, we try again with a different set of Coordinates: $nearestLongLat = sortByNearestLatLong($arrGeoData, 25.6000, -84.15000); var_dump($nearestLongLat);. This produces:

array (size=2)
  'latitudes' => 
    array (size=1)
      0 => 
        array (size=4)
          'zipcode' => int 28299
          'latitude' => float 36.234982
          'longitude' => float -81.913799
          'cityname' => string 'ACME' (length=4)
  'longitudes' => 
    array (size=1)
      0 => 
        array (size=4)
          'zipcode' => int 28299
          'latitude' => float 36.234982
          'longitude' => float -81.913799
          'cityname' => string 'ACME' (length=4)
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Solution:

Consider:

$cities = <your array>;

$point = array(
    'latitude' => 50.6000,
    'longitude' => -74.15000
);

function distance($a, $b) {
    return sqrt(
        pow($a['latitude'] - $b['latitude'], 2)
        + pow($a['longitude'] - $b['longitude'], 2));
}

usort($cities, function($p, $q) {
    global $point;
    return distance($p, $point) - distance($q, $point);
});
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This uses the naive Euclidean distance formula, for more accurate calculations replacedistance with one of the formulae listed here: https://en.wikipedia.org/wiki/Geographical_distance

Solution:

I think I can combine the calculation and return the full array in order a little better if I do it like this. Will need to do some testing but it looks correct so far. @poiz

function sort2ByNearestLatLong($geoData, $lat, $long, $returnNearestOnly=false){

    $arrCloseMatch = array();
    $matchedGeoSet = array();

    // LOOP THROUGH ALL THE $geoData ARRAY AND SUBTRACT THE GIVEN LAT & LONG VALUES
    // FROM THOSE CONTAINED IN THE ORIGINAL ARRAY: $geoData
    // WE KNOW THAT THE SMALLER THE RESULT OF THE SUBTRACTION; THE CLOSER WE ARE
    // WE DO THIS FOR BOTH THE LONGITUDE & LATITUDE... HENCE OUR ARRAY 
    // $arrClostMatch and add the values calculated for Lat/Lon:
    foreach($geoData as $iKey=>$arrGeoStrip){
        $arrCloseMatch[$iKey] = abs(floatval( ($arrGeoStrip['latitude'])  - $lat )) + abs(floatval( ($arrGeoStrip['longitude']) - $long ));
    }

    // SORT ARRAY NUMERICALLY KEEPING THE KEYS WHICH WE NEED FOR OUR FINAL RESULT
    asort($arrCloseMatch, SORT_NUMERIC);

    // RETURN CLOSEST OR FULL LIST
    foreach($arrCloseMatch as $index=>$difference){

            $matchedGeoSet['latitudes'][]  = $geoData[$index];
            if ($returnNearestOnly==true) {
                    break;
            }
   }

   return $matchedGeoSet;
}
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