I did it generating several term lists. I call it later by my own order. I'm a PHP beginner.
First, I store, in a different variable, the ID for each category term:
$terms = get_terms('my_taxonomy', 'hide_empty=0');
foreach ( $terms as $term ) {
${$term->slug} = get_term_by('slug', $term->slug, 'product_cat');
${$term->slug.'_array'} = (array)${$term->slug};
${$term->slug.'_array_id'} =${$term->slug.'_array'}['term_id'];
};
Then, I create several args for each wp_list_categories()
excluding, with this variable the terms I want to:
$args = array(
'taxonomy' => 'my_taxonomy',
'orderby' => 'name',
'show_count' => true,
'pad_counts' => false,
'hierarchical' => true,
'title_li' => '',
'hide_empty' => 0,
'show_option_all' => 'Show all',
'exclude' => array( $term1_array_id, $term2_array_id )
);
$args_1 = array(
'taxonomy' => 'my_taxonomy',
'orderby' => 'name',
'show_count' => true,
'pad_counts' => false,
'hierarchical' => true,
'title_li' => '',
'hide_empty' => 0,
'exclude' => array( $term3_array_id, $term4_array_id, $term1_array_id )
);
$args_2 = array(
'taxonomy' => 'my_taxonomy',
'orderby' => 'name',
'show_count' => true,
'pad_counts' => false,
'hierarchical' => true,
'title_li' => '',
'hide_empty' => 0,
'exclude' => array( $term1_array_id, $term4_array_id, $term5_array_id )
);
Finally, I can call separately each term list:
<ul>
<?php wp_list_categories( $args ); ?>
<?php wp_list_categories( $args_1 ); ?>
<?php wp_list_categories( $args_2 ); ?>
</ul>