Question

I have an XML file that has the following data in…

<posts>
  <post id="22359">
    <postviews>31</postviews>
  </post>
  <post id="20963">
    <postviews>1</postviews>
  </post>
  <post id="20595">
    <postviews>3</postviews>
  </post>
  <post id="22640">
    <postviews>72</postviews>
  </post>
  <post id="22227">
    <postviews>1</postviews>
  </post>
...etc etc
</posts>

I’d like to find the top 10 highest postview values and then get the parent node post id so I’d essentially have the id’s of the top 10 postviews.

I have no idea how to go about this, can anyone help? Is the XML file already an array if I load it via…

$xml = simplexml_load_file($xmlFile);

Thanks, James

Answer 1

It can be done by adding each post SimpleXML element to an array, and then sorting that array using usort():

function cmp($a, $b){
    if ((int)$a->postviews[0] == (int)$b->postviews[0]) {
        return 0;
    }
    return ((int)$a->postviews[0] > (int)$b->postviews[0]) ? -1 : 1;
}

$xml = simplexml_load_string($xmlStr);

$posts = array();

foreach($xml->post as $p)
{
    $posts[] = $p;
}

usort($posts, "cmp");

// $posts is now sorted by the views

// output them
foreach($posts as $post)
{
  echo "Post ID " . $post->attributes()->id . " has " . (int)$post->postviews . " views\n";
}

If you only want the top 10 then just use a for loop or add a check to stop the loop after the first 10, or you can unset() everything after the first 10.

Outputs

Post ID 22640 has 72 views
Post ID 22359 has 31 views
Post ID 20595 has 3 views
Post ID 22227 has 1 views
Post ID 20963 has 1 views

Codepad Demo