Similarity based shape navigation v2

shape-nav.php

<?php
$imgdir = 'snapshot-repo/';
$allowed_types = array('jpg');


$dimg = opendir($imgdir);
while($imgfile = readdir($dimg))
  {
    if(in_array(strtolower(substr($imgfile,-3)),$allowed_types))
      {
	$a_img[] = $imgfile;
	sort($a_img);
	reset ($a_img);
      }
  }
$totimg = count($a_img); // total image number

if (isset($_GET['id'])){
  $shape_id = $_GET['id'];
  $array = explode(",",exec("sed -n '".$shape_id.",1p' ".$imgdir."rank.matrix"));
}
else {
  $shape_id = 0;
  $array = range(1, $totimg);
}

echo "<title>Click to Navigate!</title>";

echo "<table align='center'><tr>";
for($x=0; $x < $totimg; $x++)
  {
    // create rows of 10
    if ($x != 0) {
      echo '<td><a href="index.php?id='.$array[$x].'"><img src="'.$imgdir.$array[$x].'.jpg" /></a><br />';
    } else {
      echo '<td><a href="index.php?id='.$array[$x].'"><img src="'.$imgdir.$array[$x].'.jpg" border="1"/></a><br />';
    }
    echo '</td>';
    
    //close the row if count / 4 = 0
    if ($x % 10 == 9){
      echo "</tr><tr>";
    }   
  }
 
//add empty cells to table to handle not having 4 images on last row
$remainder = ($totimg % 4);
 
if ($remainder > 0 ) {
  for ($x=0; $x<$remainder; $x++){
    echo "<td>&nbsp;</td>";
  }
}
 
//close table
echo "</tr></table>";
 
//echo random image
//echo $totimg.'<br />';
//$oneless = ($totimg - 1);
//$rand = rand(1, $oneless);
//echo '<img src="'.$a_img[$rand].'" /><br />'; 
//echo '<strong>'.$a_img[$rand].'</strong>'; 
  
?>