A couple of (hopefully) useful API functions that would have sat well in Drupal 7. Use them to insert an element into an array with string keys (where array_slice won't do)E.g:$element = array('dog' => 'bruce', 'elephant' => 'nelly', 'lion' => 'paws');element_insert_after($element, array('cat' => 'pussy'), 'dog') would give:array('dog' => 'bruce…

element_insert.php

<?php
/**
 * Insert an element into an associative array after a specified key.
 *
 * @see _element_insert()
 */
function element_insert_after(&$element, $insert, $key) {
  _element_insert(TRUE, $element, $insert, $key);
}

/**
 * Insert an element into an associative array before a specified key.
 *
 * @see _element_insert()
 */
function element_insert_before(&$element, $insert, $key) {
  _element_insert(FALSE, $element, $insert, $key);
}

/**
 * Insert or move an item or items in an associative array at a defined point.
 *
 * @param bool $after
 *   Set to TRUE to insert $insert AFTER $key in $element, FALSE to insert
 *   $insert BEFORE $key in $element.
 * @param array $element
 *   An associative array which is to be manipulated.
 * @param string|array $insert
 *   Either a key in $element to be moved, or a new associative array to be
 *   inserted.
 * @param string $key
 *   The point within $element that $insert should be placed, such that if
 *   $after is TRUE, then elements within $insert will be placed immediately
 *   following $key.
 *
 */
function _element_insert($after, &$element, $insert, $key) {
  if (!is_array($insert) && isset($element[$insert])) {
    $insert = array($insert => $element[$insert]);
  }

  $new = array();
  while (list($k, $v) = each($element)) {
    if ($after) {
      $new[$k] = $v;
    }
    if ($k === $key) {
      $element = $new + $insert + $element;
      return;
    }
    if (!$after) {
      $new[$k] = $v;
    }
  }
}