通过索引偶数或奇数将数组拆分为两个数组

Question

我有这个数组:

$array = array(a, b, c, d, e, f, g);

我希望将它拆分为两个数组,具体取决于索引是偶数还是奇数,如下所示:

$odd = array(a, c, e, g);

$even = array(b, d, f);

提前致谢!

Answer 1

一种解决方案,使用匿名函数和array_walk:

$odd = array();
$even = array();
$both = array(&$even, &$odd);
array_walk($array, function($v, $k) use ($both) { $both[$k % 2][] = $v; });

这只是在数组中一次传递中分隔项目,但它在"聪明"方面有点过分.它并不比经典更好,更冗长

$odd = array();
$even = array();
foreach ($array as $k => $v) {
    if ($k % 2 == 0) {
        $even[] = $v;
    }
    else {
        $odd[] = $v;
    }
}

Answer 2

用途array_filter:

$odd = array_filter($array, function ($input) {return $input & 1;}, ARRAY_FILTER_USE_KEY);
$even = array_filter($array, function ($input) {return !($input & 1);}, ARRAY_FILTER_USE_KEY);

Answer 3

作为一个几乎单行的人，我认为这将是我最喜欢的：

\n\n

$even = $odd = array();\nforeach( $array as $k => $v )  $k % 2  ?  $odd[] = $v  :  $even[] = $v;\n

\n\n

或者再多一点点？速度：

\n\n

$even = $odd = array();\nforeach( $array as $k => $v )  ( $k & 1 ) === 0  ?  $even[] = $v  :  $odd[] = $v;\n

\n\n

更详细一点的变体：

\n\n

$both = array( array(), array() );\n// or, if $array has at least two elements:\n$both = array();\n\nforeach( $array as $k => $v )  $both[ $k % 2 ][] = $v;\nlist( $even, $odd ) = $both;\n

\n\n

和array_chunk：

\n\n

$even = $odd = array();\nforeach( array_chunk( $array, 2 ) as $chunk ){\n  list( $even[], $odd[] ) = isset( $chunk[1]) ? $chunk : $chunk + array( null, null );\n  // or, to force even and odd arrays to have the same count:\n  list( $even[], $odd[] ) = $chunk + array( null, null );\n}\n

\n\n

如果保证 $array 有偶数个元素：

\n\n

$even = $odd = array();\nforeach( array_chunk( $array, 2 ) as $chunk )\n  list( $even[], $odd[] ) = $chunk;\n

\n\n

PHP 5.5.0+ 具有array_column：

\n\n

$chunks = array_chunk( $array, 2 );\n$even = array_column( $chunks, 0 );\n$odd  = array_column( $chunks, 1 );\n

\n\n

旧 PHP 版本的情况类似。\n密钥将为 0,2,4,\xe2\x80\xa6 和 1,3,5,\xe2\x80\xa6。如果你不喜欢这个，array_values也可以应用：

\n\n

$even = array_intersect_key( $array, array_flip( range( 0, count( $array ), 2 )));\n$odd  = array_intersect_key( $array, array_flip( range( 1, count( $array ), 2 )));\n

\n\n

或者

\n\n

$even = array_intersect_key( $array, array_fill_keys( range( 0, count( $array ), 2 ), null ));\n$odd  = array_intersect_key( $array, array_fill_keys( range( 1, count( $array ), 2 ), null ));\n

\n

Answer 4

我不确定这是否是最优雅的方式，但它应该很有魅力：

$odd=array();
$even=array();
$count=1;
foreach($array as $val)
{
    if($count%2==1)
    {
        $odd[]=$val;
    }
    else
    {
        $even[]=$val;
    }
    $count++;
}