Wordpress Portfolio Categories in Dropdown instead of tabs

Question

The code that retrieves the categories in tab filter is:

<!-- BEGIN .filter-tabs -->
                        <ul class="filter-tabs filt-tabs clearfix">
                            <li class="selected"><a href="#" title="<?php _e('View all All items','hbthemes'); ?>" class="all" data-filter="*"><span class="item-name"><?php _e('All','hbthemes'); ?></span><span class="item-count">0</span></a></li>
                            <?php if ( !empty($portfolio_filters) ) { 
                                foreach ( $portfolio_filters as $slug=>$name ) { ?>
                                    <li>
                                        <a href="#" data-filter=".<?php echo $slug; ?>" title="<?php _e('View all ','hbthemes'); echo $name; _e(' items','hbthemes'); ?>">
                                            <span class="item-name"><?php echo $name; ?><span class="item-count">0</span></span>
                                        </a>
                                    </li>
                            <?php
                                } 
                            }
                            ?>
                        </ul>
                    <!-- END .filter-tabs -->

May I kindly know how can I display the same categories in a dropdown control instead of tabs?

Appreciate your help