WordPress: find all post thumbnails that match criteria // remove those unfitting

gistfile1.php

<?php
    $args = array('posts_per_page' => -1); // get all posts
    $attachments = get_posts( $args );
    $allP = 0;
    $wThumb = 0;
    $great = 0;
    $ok = 0;
    $wrong = 0;
    if ( $attachments ) {
      foreach ( $attachments as $post ) {
        $allP++;
        if(has_post_thumbnail()) {
          $wThumb++;
          $url = wp_get_attachment_url( get_post_thumbnail_id($post->ID) );
          $size = getimagesize($url);
          if($size[0] >= 710 && $size[1] >= 355) {
            $great++;
          } elseif($size[0] >= 330 && $size[1] >= 165) {
            $ok++;
          } else {
            $wrong++;
            if($size[0] == 0) {
              echo "Deleted post thumbnail for <a href=\"" . get_permalink() . "\">" . get_the_title() . "</a> because post thumbnail couldn't be found<br />";
            } else {
              echo "Deleted post thumbnail for <a href=\"" . get_permalink() . "\">" . get_the_title() . "</a> because post thumbnail had size " . $size[0] . " × " . $size[1] . "<br />";
            }
            //delete_post_thumbnail($post->ID);
          }
        }
      }
      echo "found <strong>" . $allP . "</strong> posts<br /><br />";
      echo "found <strong>" . $wThumb . "</strong> posts with thumbnails<br /><br />";
      echo $great . " are ok<br />";
      echo $ok . " are ok (for post listing)<br />";
      echo $wrong . " are too small or missing<br />";
    }
    die;
?>