如果包含小写字母，则从数组中删除

I have a number of WordPress posts that will each have two tags, one tag is the State and the other tag is an Airport Code.

I'm able to generate a dropdown menu from the tags using the instructions here: http://www.wprecipes.com/wordpress-hack-display-your-tags-in-a-dropdown-menu

But, I would like to actually have two different dropdowns, one that lists the States in alpha order, the other lists the Airports in alpha order. Every Airport will always be three uppercase letters. Is there an argument that I can add to to this so that I can create one dropdown for Airports and another for States?

If it contains a lowercase letter, it goes in the State dropdown. If no lowercase, it's an airport.

I modify the snippet from your attached tutorials into something like this:

function dropdown_tag_cloud( $args = '' ) {//supported: 'all', 'airport', 'state'
    $defaults = array(
        'smallest' => 8, 'largest' => 22, 'unit' => 'pt', 'number' => 45,
        'format' => 'flat', 'orderby' => 'name', 'order' => 'ASC',
        'exclude' => '', 'include' => '', 'tags_mode' => 'all'
    );
    $args = wp_parse_args( $args, $defaults );

    print_r($args);


    $tags = get_tags( array_merge($args, array('orderby' => 'count', 'order' => 'DESC')) ); // Always query top tags

    if ( empty($tags) )
        return;

    $return = dropdown_generate_tag_cloud( $tags, $args ); // Here's where those top tags get sorted according to $args
    if ( is_wp_error( $return ) ){
        echo "wp error...";
        return false;
    }else
        echo apply_filters( 'dropdown_tag_cloud', $return, $args );
}

function dropdown_generate_tag_cloud( $tags, $args = '' ) {
    global $wp_rewrite;
    $defaults = array(
        'smallest' => 8, 'largest' => 22, 'unit' => 'pt', 'number' => 45,
        'format' => 'flat', 'orderby' => 'name', 'order' => 'ASC'
    );
    $args = wp_parse_args( $args, $defaults );
    extract($args);

    if ( !$tags )
        return;
    $counts = $tag_links = array();
    foreach ( (array) $tags as $tag ) {

        if($tags_mode == 'airport'){

            //if uppercased tag is equal to the tag
            //which means current tag already uppercased.
            if(!(strtoupper($tag->name) == $tag->name))
                continue;//skip current tag

        } else if($tags_mode == 'state'){
            //if uppercased tag is equal to the tag
            //which means current tag already uppercased.
            if((strtoupper($tag->name) == $tag->name))
                continue;//skip current tag
        }

        $counts[$tag->name] = $tag->count;
        $tag_links[$tag->name] = get_tag_link( $tag->term_id );
        if ( is_wp_error( $tag_links[$tag->name] ) )
            return $tag_links[$tag->name];
        $tag_ids[$tag->name] = $tag->term_id;
    }

    $min_count = min($counts);
    $spread = max($counts) - $min_count;
    if ( $spread <= 0 )
        $spread = 1;
    $font_spread = $largest - $smallest;
    if ( $font_spread <= 0 )
        $font_spread = 1;
    $font_step = $font_spread / $spread;

    // SQL cannot save you; this is a second (potentially different) sort on a subset of data.
    if ( 'name' == $orderby )
        uksort($counts, 'strnatcasecmp');
    else
        asort($counts);

    if ( 'DESC' == $order )
        $counts = array_reverse( $counts, true );

    $a = array();

    $rel = ( is_object($wp_rewrite) && $wp_rewrite->using_permalinks() ) ? ' rel="tag"' : '';

    foreach ( $counts as $tag => $count ) {
        $tag_id = $tag_ids[$tag];
        $tag_link = clean_url($tag_links[$tag]);
        $tag = str_replace(' ', '&nbsp;', wp_specialchars( $tag ));
        $a[] = "\t<option value='$tag_link'>$tag ($count)</option>";
    }

    switch ( $format ) :
    case 'array' :
        $return =& $a;
        break;
    case 'list' :
        $return = "<ul class='wp-tag-cloud'>
\t<li>";
        $return .= join("</li>
\t<li>", $a);
        $return .= "</li>
</ul>
";
        break;
    default :
        $return = join("
", $a);
        break;
    endswitch;

    return apply_filters( 'dropdown_generate_tag_cloud', $return, $tags, $args );
}

Basically, I was just adding new parameter called tags_mode with the following parameter supported:

all
airport
state

And then, in dropdown_generate_tag_cloud(), I add this code:

    if($tags_mode == 'airport'){

        if(!(strtoupper($tag->name) == $tag->name))
            continue;//skip current tag

    } else if($tags_mode == 'state'){
        if((strtoupper($tag->name) == $tag->name))
            continue;//skip current tag
    }

The main idea in this added snippet is this:

strtoupper($tag->name) == $tag->name

It work like this: if the uppercased tag name is equal to the original tag name. That means, current tag is already uppercased (or, equal to airport code).

To implement it, just do as the tutorial says. Only, you need to add new parameter:

<?php dropdown_tag_cloud('number=0&order=asc&tags_mode=state'); ?>

Notice the &tags_mode=state

Just try it out and tell me if this is what you want.