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Convert GPS Degrees and Minutes to decimal using Coldfusion

I have a routine that needs to run through a database and convert Degrees and Minutes into a decimal equivalent, but I have no idea how to do it. Below are two examples.

Example 1.
Position: 12° 58.405' S, 38° 30.663' W
Lng = 12° 58.405' S
Lat = 38° 30.663' W

Example 2.
Position: 41° 14.81' N, 73° 47.019' W
Lat = 41° 14.81' N
Lng = 73° 47.019' W

ASKER CERTIFIED SOLUTION

Jaime Olivares

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MTP_Phil

ASKER

OK... I get the math. But how do I do it programmatically? I have what amounts to a text field with "12° 58.405' S" in it. How do i separate it out to do the math?

Ray Paseur

I don't know ColdFusion, but here is an example in PHP. Maybe a PHP + CF expert will come along and convert the code.
http://www.laprbass.com/RAY_temp_mtp_phil.php

<?php // RAY_temp_mtp_phil.php
error_reporting(E_ALL);

// CONVERT LAT/LON NOTATION TO GEOCODE

// SOME TEST DATA
$points[] = " 12° 58.405' S, 38° 30.663' W";
$points[] = " 41° 14.81' N, 73° 47.019' W";
$points[] = "38° 50.051' N, 77° 8.9602' W";

$geocodes[] = '41.902916,12.453389';
$geocodes[] = '38.834175,-77.149336';

// A REGULAR EXPRESSION TO REMOVE UNWANTED CHARACTERS
$rgx
= '#'             // REGEX DELIMITER
. '['             // CHARACTER CLASS
. '^'             // NEGATION: MATCH SET THEORY COMPLEMENT
. '0-9., NESW'    // ACCEPTABLE CHARACTERS
. ']'             // END CHARACTER CLASS
. '#'             // REGEX DELIMITER
;

// MAKE TEST CASES
foreach ($points as $point)
{
    // NORMALIZE THE DATA AND BREAK ON COMMA
    $pnt = strtoupper($point);
    $pnt = preg_replace($rgx, NULL, $pnt);
    $arr = explode(',', $pnt);

    // ENSURE ONLY SINGLE BLANKS
    $lat = trim(preg_replace('#\s\s+#', ' ', $arr[0]));
    $lon = trim(preg_replace('#\s\s+#', ' ', $arr[1]));

    // BREAK ON BLANKS AND RECONSTRUCT A DECIMAL VALUE
    $xyz = explode(' ', $lat);
    $lat = $xyz[0] + $xyz[1] / 60.0;
    $lat = number_format($lat,7);
    if ($xyz[2] == 'S') $lat = $lat * -1.0;

    // BREAK ON BLANKS AND RECONSTRUCT A DECIMAL VALUE
    $xyz = explode(' ', $lon);
    $lon = $xyz[0] + $xyz[1] / 60.0;
    $lon = number_format($lon,7);
    if ($xyz[2] == 'W') $lon = $lon * -1.0;

    // SHOW THE WORK PRODUCT WITH MAP POINTERS
    echo "<br/>";
    echo "<a target='_blank' href=\"https://maps.google.com/maps?q=" . htmlentities($point) . "&hl=en&z=14\">POSITION: $pnt</a>";
    echo ' == ';
    echo "<a target='_blank' href=\"https://maps.google.com/maps?q=$lat,$lon&hl=en&z=14\">GEOCODE: $lat,$lon</a>" . PHP_EOL;
}
echo '<br/>' . PHP_EOL;

// MAKE TEST CASES TO CONVERT GEOCODE TO POINT
foreach ($geocodes as $geocode)
{
    // CONSTRUCT STRING HERE
    $point = NULL;

    // SEPARATE LAT AND LON
    $arr = explode(',', $geocode);
    $lat = trim(preg_replace('#[^0-9-.]#', NULL, $arr[0]));
    $lon = trim(preg_replace('#[^0-9-.]#', NULL, $arr[1]));

    // COMPUTE DEGREES, MINUTES, ETC
    $xyz = explode('.', $lat);
    $deg = $xyz[0] . '° ';
    $min = '0.' . $xyz[1];
    $min = $min * 60.0;
    $min = $min . "' ";
    if (strpos($deg, '-') === FALSE)
    {
        $min .= 'N';
    }
    else
    {
        $min .= 'S';
    }
    $deg = str_replace('-', NULL, $deg);
    $point .= $deg . $min . ', ';

    // COMPUTE DEGREES, MINUTES, ETC
    $xyz = explode('.', $lon);
    $deg = $xyz[0] . '° ';
    $min = '0.' . $xyz[1];
    $min = $min * 60.0;
    $min = $min . "' ";
    if (strpos($deg, '-') === FALSE)
    {
        $min .= 'E';
    }
    else
    {
        $min .= 'W';
    }
    $deg = str_replace('-', NULL, $deg);
    $point .= $deg . $min;

    // SHOW THE WORK PRODUCT WITH MAP POINTERS
    echo "<br/>";
    echo "<a target='_blank' href=\"https://maps.google.com/maps?q=" . htmlentities($point) . "&hl=en&z=14\">POSITION: $point</a>";
    echo ' == ';
    echo "<a target='_blank' href=\"https://maps.google.com/maps?q=$lat,$lon&hl=en&z=14\">GEOCODE: $lat,$lon</a>" . PHP_EOL;
}

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MTP_Phil

ASKER

Thank you for providing the math. I eventually found a way to separate the various elements and apply the math using ColdFusion.