Find centerpoint of polygon in JavaScript

Question

I have a \"place\" object from Google Maps which has a set of coordinates that represent a bounding box for a given location, say London. Each set of coordinates has a latit

Answer 1

I realize this is not exactly what you are looking for, but in case no one else answers it may be of some help. This is a PHP function which I use to to find the center point of polygons for my map application. It should be fairly easily converted to javascript for your use.

function getCenter($coord_array){
    $i = 0;
    $center = $coord_array[0];
    unset($coord_array[0]);
    foreach($coord_array as $key => $coord){    
        $plat = $coord[0];
        $plng = $coord[1];
        $clat = $center[0];
        $clng = $center[1];
        $mlat = ($plat + ($clat * $i)) / ($i + 1);
        $mlng = ($plng + ($clng * $i)) / ($i + 1);
        $center = array($mlat, $mlng);
        $i++;
    }
    return array($mlat, $mlng);
}

Note that the polygon has to be closed, meaning the first point in the array and the last point in the array are the same.

The function that converts the coordinate string to the necessary array:

function coordStringToArray($coord_string)
{
    $coord_array = explode("\n",$coord_string);
    foreach($coord_array as $key => $coord){
        $coord_array[$key] = explode(', ',$coord);
    }
    return $coord_array;
}

A sample of the raw coordinate string:

42.390576, -71.074258
42.385822, -71.077091
42.382461, -71.079408
42.382018, -71.081468
42.380496, -71.080953
42.380433, -71.076576
42.373902, -71.073915
42.373078, -71.069967
42.369273, -71.064216
42.368892, -71.062328
42.369527, -71.056491
42.370288, -71.050741
42.371619, -71.047908
42.376185, -71.046278
42.383476, -71.045763
42.386139, -71.050483
42.386202, -71.057693
42.387597, -71.066534
42.390259, -71.072284
42.391210, -71.073658