convert.php

<?php

/*
 * Convert DMS (degrees / minutes / seconds) to decimal degrees
 *
 * Todd Trann
 * May 22, 2015
 */
function convertDMSToDecimal($latlng) {
    $valid = false;
    $decimal_degrees = 0;
    $degrees = 0; $minutes = 0; $seconds = 0; $direction = 1;

    // Determine if there are extra periods in the input string
    $num_periods = substr_count($latlng, '.');
    if ($num_periods > 1) {
        $temp = preg_replace('/\./', ' ', $latlng, $num_periods - 1); // replace all but last period with delimiter
        $temp = trim(preg_replace('/[a-zA-Z]/','',$temp)); // when counting chunks we only want numbers
        $chunk_count = count(explode(" ",$temp));
        if ($chunk_count > 2) {
            $latlng = preg_replace('/\./', ' ', $latlng, $num_periods - 1); // remove last period
        } else {
            $latlng = str_replace("."," ",$latlng); // remove all periods, not enough chunks left by keeping last one
        }
    }
    
    // Remove unneeded characters
    $latlng = trim($latlng);
    $latlng = str_replace("º"," ",$latlng);
    $latlng = str_replace("°"," ",$latlng);
    $latlng = str_replace("'"," ",$latlng);
    $latlng = str_replace("\""," ",$latlng);
    $latlng = str_replace("  "," ",$latlng);
    $latlng = substr($latlng,0,1) . str_replace('-', ' ', substr($latlng,1)); // remove all but first dash

    if ($latlng != "") {
    	// DMS with the direction at the start of the string
        if (preg_match("/^([nsewNSEW]?)\s*(\d{1,3})\s+(\d{1,3})\s+(\d+\.?\d*)$/",$latlng,$matches)) {
            $valid = true;
            $degrees = intval($matches[2]);
            $minutes = intval($matches[3]);
            $seconds = floatval($matches[4]);
            if (strtoupper($matches[1]) == "S" || strtoupper($matches[1]) == "W")
                $direction = -1;
        }
        // DMS with the direction at the end of the string
        elseif (preg_match("/^(-?\d{1,3})\s+(\d{1,3})\s+(\d+(?:\.\d+)?)\s*([nsewNSEW]?)$/",$latlng,$matches)) {
            $valid = true;
            $degrees = intval($matches[1]);
            $minutes = intval($matches[2]);
            $seconds = floatval($matches[3]);
            if (strtoupper($matches[4]) == "S" || strtoupper($matches[4]) == "W" || $degrees < 0) {
                $direction = -1;
                $degrees = abs($degrees);
            }
        }
        if ($valid) {
            // A match was found, do the calculation
            $decimal_degrees = ($degrees + ($minutes / 60) + ($seconds / 3600)) * $direction;
        } else {
            // Decimal degrees with a direction at the start of the string
            if (preg_match("/^([nsewNSEW]?)\s*(\d+(?:\.\d+)?)$/",$latlng,$matches)) {
                $valid = true;
                if (strtoupper($matches[1]) == "S" || strtoupper($matches[1]) == "W")
                    $direction = -1;
                $decimal_degrees = $matches[2] * $direction;
            }
            // Decimal degrees with a direction at the end of the string
            elseif (preg_match("/^(-?\d+(?:\.\d+)?)\s*([nsewNSEW]?)$/",$latlng,$matches)) {
                $valid = true;
                if (strtoupper($matches[2]) == "S" || strtoupper($matches[2]) == "W" || $degrees < 0) {
                    $direction = -1;
                    $degrees = abs($degrees);
                }
                $decimal_degrees = $matches[1] * $direction;
            }
        }
    }
    if ($valid) {
        return $decimal_degrees;
    } else {
        return false;
    }
}


// Code below here is not needed, only for testing the above


$test_cases = array(
    " N 53 03 47.7 "," s53 03 47.7"," E53  03  47.7"," w53 03 47.7 ","  53 03 47.7 n"," 53 03 47.7S",
    " 53  03  47.7e "," W 53 03 47.7 "," N53 03 47.7"," s.53.03.47.7 "," E53.03.47.7"," w53..03..47.7",
    " n53.03.47.7 ","  53.03.47.7 S"," 53.03.47.7e"," 53..03..47.7W "," N.53.03.47.7 "," s53.03.47.7",
    " E-53-03-47.7 "," w53-03-47.7"," n53--03--47.7"," S53-03-47.7 ","  53-03-47.7 e"," 53-03-47.7W",
    " 53--03--47.7N "," s-53-03-47.7 "," E53-03-47.7","53.06325w","53.06325","53.06325 s",
    "53.06325 N","-53.06325","53 03 47.7","-53 03 47.7","53 03 47.7W","-53º 03' 47.7\"",
    "53º 03' 47.7\"","53º 03' 47.7\"s"," N 144 35 26"," s144 35 26","E 144  35 26","144 35 26w",
    "N144.35.26"," 144.35.26s","-144 35 26","144º 35' 26\"w","45°43'51''N","009°44'23''E"
);

foreach ($test_cases as $t) {
    echo $t . "\t=>\t" . convertDMSToDecimal($t) . "\n";
}

?>