php数组拆分、组合

有一个数组：
Array
(
    [0] => 15461209
    [1] => 12
    [2] => 12
    [3] => 1055088
    [4] => 1
    [5] => admin
    [6] => 1
    [7] => hgtbrshbtyrws
    [8] => 1366010391
    [9] => hntyrhnrytwsnhbyrtnhb
    [10] => 127.0.0.1
    [11] => 0
    [12] => 0
    [13] => 1
    [14] => 0
    [15] => -1
    [16] => -1
    [17] => 0
    [18] => 0
    [19] => 0
    [20] => 0
    [21] => 0
    [22] => 
    [23] => 0
    [24] => 15461210
    [25] => 12
    [26] => 12
    [27] => 1055088
    [28] => 0
    [29] => admin
    [30] => 1
    [31] => 
    [32] => 1366075840
    [33] => 111111111111111
    [34] => 127.0.0.1
    [35] => 0
    [36] => 0
    [37] => 1
    [38] => 0
    [39] => -1
    [40] => -1
    [41] => 0
    [42] => 0
    [43] => 0
    [44] => 0
    [45] => 0
    [46] => 0
    [47] => 0
)
想在想变成这种形式：
Array
(
    [0] => Array
        (
            [pid] => 15461209
            [fid] => 12
            [tid] => 1055088
            [first] => 1
            [author] => admin
            [authorid] => 1
            [subject] => hgtbrshbtyrws
            [dateline] => 1366010391
            [message] => hntyrhnrytwsnhbyrtnhb
            [useip] => 127.0.0.1
            [invisible] => 0
            [anonymous] => 0
            [usesig] => 1
            [htmlon] => 0
            [bbcodeoff] => -1
            [smileyoff] => -1
            [parseurloff] => 0
            [attachment] => 0
            [rate] => 0
            [ratetimes] => 0
            [status] => 0
            [tags] => 
            [comment] => 0
        )

    [1] => Array
        (
            [pid] => 15461210
            [fid] => 12
            [tid] => 1055088
            [first] => 0
            [author] => admin
            [authorid] => 1
            [subject] => 
            [dateline] => 1366075840
            [message] => 111111111111111
            [useip] => 127.0.0.1
            [invisible] => 0
            [anonymous] => 0
            [usesig] => 1
            [htmlon] => 0
            [bbcodeoff] => -1
            [smileyoff] => -1
            [parseurloff] => 0
            [attachment] => 0
            [rate] => 0
            [ratetimes] => 0
            [status] => 0
            [tags] => 0
            [comment] => 0
        )

)
写个循环，把想要的数组组合出来，该如何写？考虑性能问题

回复讨论(解决方案)

array_chunk + array_combine

http://www.w3school.com.cn/php/php_ref_array.asp
来，挑一个吧

$arr=你的数组..$key=array (  0 => 'pid',  1 => 'fid',  2 => 'tid',  3 => 'first',  4 => 'author',  5 => 'authorid',  6 => 'subject',  7 => 'dateline',  8 => 'message',  9 => 'useip',  10 => 'invisible',  11 => 'anonymous',  12 => 'usesig',  13 => 'htmlon',  14 => 'bbcodeoff',  15 => 'smileyoff',  16 => 'parseurloff',  17 => 'attachment',  18 => 'rate',  19 => 'ratetimes',  20 => 'status',  21 => 'tags',  22 => 'comment',);foreach(array_chunk($arr,24) as $v){     array_splice($v,1,1);     $ar[]=array_combine($key,$v);}print_r($ar);