请教各位php组合生成一个特殊数组的问题

就是大数组里面的第一个小数组永远是最长的 ... 如果在这个数组里有 false 值则补全其他为空白 ...
写了段示例代码如下

<?php
/* your array puts here ... primary key must be the first entry ... */
$arr = [
    'id'    =>  [ '1', false, '3', '4' ],
    'name'  =>  [ 'zhang', 'li', 'du' ]
];

/* get all key names ... */
$keys = array_keys( $arr );

/* use a different way to solve this ... */
var_export( array_reduce( $arr, 
    function( & $result, $current ) use ( & $keys ) {

    /* get current key name ... */
    $key = array_shift( $keys );

    /* first run ..? */
    if ( ! isset( $result ) )

        /* initialize a new array with primary key... */
        $result = array_map( function( $value ) use ( $key ) {

            /* just packing value as an array ... */
            return [ $key => $value ];

        /* value based on $current ... known as first entry of $arr ... */
        }, $current );

    /* when the array is built ... add new keys into it ... */
    else foreach ( $result as $num => & $value )

        /* leave blank when primary key is false or entry is empty ... */
        $value[$key] = ( false !== current( $value ) ) ?
            array_shift( $current ) ?: '' : '';

    /* send the new array back ... */
    return $result;

} ) );

原理就是根据原数组里面的第一个小数组建立主键 ... 然后根据主键把所有元素拼合在一起 ...