Getting data from xml file and plotting in plotting in php

I'm reading through an xml file to get data. The xml looks like this:

<packet>
<item>
     <timestamp>0</timestamp>
     <<id>10</id>
     <id>14</id>
     <id>2</id>
     <id>7</id>
     <id>6</id>
</item>
<item>
     <timestamp>1</timestamp>
     <id>4</id>
     <id>4</id>
     <id>8</id>
     <id>3</id>
     <id>2</id>
     <id>12</id>
</item>
...
</packet>

I cut the xml file because its long. The number of id within each timestamp varies. I already got the code to read through the xml file

<?php
if(file_exists('myfile.xml'))
{
  $xml = simplexml_load_file ("myfile.xml");
}
else {
  exit ('Could not load the file...');
}

foreach($xml->item as $item)
{
   echo $item->timestamp.'<br>';
   {
      foreach($item->id as $id)
      {
        echo $id.' ';
      }
      echo '<br>';
      echo '<br>';
   }
}

And the result is something like this

0
10 14 2 7 6

1
4 4 8 3 2 12

I just don't know how to got about plotting this in php in such a way that the timestamp is on the x-axis and the id gets plotted on the y-axis