PHP排序维度关联数组，同时保留数组键

我见过这样的阵列

<?php

$a = array(
    "2" => array(
        "v" => 1
    ),
    "3" => array(
        "v" => 2
    )
);

usort($a, function($a, $b)
{
    return $a['v'] < $b['v'];
});

但我不想修改密钥，例如

Array
(
    [3] => Array
        (
            [v] => 2
        )

    [2] => Array
        (
            [v] => 1
        )

)

可能吗？

用于保留密钥

<?php

$a = array(
    "2" => array(
        "v" => 1
    ),
    "3" => array(
        "v" => 2
    )
);

uasort($a, function($a, $b)
{
    return $a['v'] < $b['v'];
});

---

使用
uasort
保存密钥
<?php

$a = array(
    "2" => array(
        "v" => 1
    ),
    "3" => array(
        "v" => 2
    )
);

uasort($a, function($a, $b)
{
    return $a['v'] < $b['v'];
});