Вывести записи по первой букве алфавита

<div class="letter-list">  
    <?php 
    $posts = get_posts(
        array(
            'post_type' => 'logos',
            'post_status' => 'publish',
            'posts_per_page' => -1,
            'orderby' => 'title',
            'order' => 'ASC',
        )
    );
    $alphas = range('A', 'Z');
    $letter_keyed_posts = array();
    if ( $posts ) {
        foreach ( $posts as $post ) {
            $first_letter = strtoupper( substr( $post->post_title, 0, 1 ) );

            if ( ! array_key_exists( $first_letter, $letter_keyed_posts ) ) {

                $letter_keyed_posts[ $first_letter ] = array();
            }

             $letter_keyed_posts[ $first_letter ][] = $post;
        }

    }
    foreach ($letter_keyed_posts as $key => $value) {
        ?>
        <ul>
            <div class="letter"><?php echo $key; ?></div>
            <?php foreach ($value as $val) {
                ?>

                <li><a href="<?php echo get_permalink( $val->ID ); ?>"><?php echo $val->post_title; ?></a></li>
                <?php
            } ?>
        </ul>
        <?php
    }
    ?>
</div>