title: Find centerpoint of polygon in JavaScript
body: <p>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 latitude and longitude.</p>
  
  <p>I have written the below code to find the centerpoint, but I am not sure if it does actually produce the centerpoint. What if the polygon has 5 points instead of 4? Also, can this be done in a more efficient way, with less operations?</p>
  
  <pre><code>function average(array) {
    // Add together and then divide by the length
    return _.reduce(array, function (sum, num) {
      return sum + num;
    }, 0) / array.length;
  }
  
  // I have a two-dimensional array that I want to get the average of
  
  var coords = [
    [ -1.2, 5.1 ],
    [ -1.3, 5.2 ],
    [ -1.8, 5.9 ],
    [ -1.9, 5.8 ]
  ]
  
  // So I get the first column
  
  var lats = coords.map(function (coord) {
    return coord[0];
  })
  
  // Then the second
  
  var longs = coords.map(function (coord) {
    return coord[1];
  })
  
  // And average each column out
  
  console.log([average(lats), average(longs)])
  </code></pre>
  
  <p><a href="http://jsbin.com/abilov/1/edit" rel="noreferrer">Example</a>.</p>