How to Calculate Distance Between Two Points Using Latitude and Longitude?

Calculating Distance Given Two Points: Latitude and Longitude

Determining the distance between points using their latitude and longitude is a common GIS task. To find points within a specified radius, we can leverage mathematical formulas and SQL queries.

Formula for Distance Calculation

One approach is to use the Haversine formula, which calculates the distance between two points on a sphere:

<code class="python">def get_distance(lat1, lon1, lat2, lon2, unit='Mi'):
    theta = lon1 - lon2
    distance = (math.sin(math.radians(lat1)) * math.sin(math.radians(lat2))) + \
              (math.cos(math.radians(lat1)) * math.cos(math.radians(lat2)) * \
              math.cos(math.radians(theta)))
    distance = math.acos(distance)
    distance = math.degrees(distance)
    distance = distance * 60 * 1.1515
    if unit == 'Km':
        distance = distance * 1.609344
    return round(distance, 2)</code>

SQL Query for Radius Search

Another option is to use a MySQL query with the distance formula:

<code class="sql">SELECT *,
(((acos(sin((".$latitude."*pi()/180)) * sin((`Latitude`*pi()/180))+cos((".$latitude."*pi()/180)) * cos((`Latitude`*pi()/180)) * cos(((".$longitude."- `Longitude`)* pi()/180))))*180/pi())*60*1.1515) as distance
FROM `MyTable` HAVING distance >= ".$distance.";</code>

By applying these methods, you can efficiently calculate the distance between points and find those within a desired radius from a given location.

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