WordPress MU

I've been trying to grab the output of wp_list_categories() in a variable so I could manipulate it some more before the final output.

I've followed suggestions here:
WordPress.org forum post

and when that didn't work, here:
WordPress.org Ideas post

No luck both times.

The hack seems straightforward enough. Here's what my wp_list_categories() in category-template.php looks like right now:

function wp_list_categories($args = '') {
 if ( is_array($args) )
  $r = &$args;
  else
  parse_str($args, $r);

  $defaults = array('show_option_all' => '', 'orderby' => 'name',
    'order' => 'ASC', 'show_last_update' => 0, 'style' => 'list',
    'show_count' => 0, 'hide_empty' => 1, 'use_desc_for_title' => 1,
    'child_of' => 0, 'feed' => '', 'feed_image' => '', 'exclude' => '',
    'hierarchical' => true, 'title_li' => __('Categories'), 'echo' => 1);
  $r = array_merge($defaults, $r);

... no changes here ...

//echo apply_filters('wp_list_categories', $output);
////old statement removed

  if(!$echo)
    return apply_filters('wp_list_categories', $output);
    else
    echo apply_filters('wp_list_categories', $output);
}

In my header.php code, I have a call like this:

<?php $cats = wp_list_categories('sort_column=id&depth=1&title_li=&exclude=1'); ?>

but the categories still display.

Am I doing something wrong? Has anyone else tried this?

Thanks,
jeff.

Grr. I got it, sorry. Wasn't being careful.

One must add "echo=0" to the list of parameters in the wp_list_categories() call, I notice. Problem solved.