如何根据嵌套最深的数组中每个集合的和值对该数组进行排序？
$arr = Array(
Array(
'I am the first string.',
Array(
Array( 'round', 1, 1 ),
Array( 'rhythm', 1, 1 )
)
),
Array(
'I am the second string',
Array(
Array( 'cps', 1, 1 ),
Array( 'Hz', 1, 3 ),
Array( 'hertz', 1, 1 )
)
),
Array(
'I am the third string.',
Array(
Array( 'uucps', 1, 1 ),
Array( 'uuHz', 1, 2 ),
Array( 'uuhertz', 1, 1 )
)
)
);
我需要根据最深集（第三维度）的第三个键的和值对数组的第二维度进行排序。
所以最终结果会是这样的：
$arr = Array(
Array(
'I am the second string',
Array(
Array( 'cps', 1, 1 ),
Array( 'Hz', 1, 3 ),
Array( 'hertz', 1, 1 )
)
),
Array(
'I am the third string.',
Array(
Array( 'uucps', 1, 1 ),
Array( 'uuHz', 1, 2 ),
Array( 'uuhertz', 1, 1 )
)
),
Array(
'I am the first string.',
Array(
Array( 'round', 1, 1 ),
Array( 'rhythm', 1, 1 )
)
)
);
我知道usort可能是我最好的选择，但我似乎无法使它适用于我的用例。
使用usort、array_sum和array_column函数的解决方案：
usort($arr, function($a, $b){
$prev = array_sum(array_column($a[1], 2)); // summing up values for each third key (2)
$next = array_sum(array_column($b[1], 2));
return $next - $prev;
});
print_r($arr);
输出：
Array
(
[0] => Array
(
[0] => I am the second string
[1] => Array
(
[0] => Array
(
[0] => cps
[1] => 1
[2] => 1
)
[1] => Array
(
[0] => Hz
[1] => 1
[2] => 3
)
[2] => Array
(
[0] => hertz
[1] => 1
[2] => 1
)
)
)
[1] => Array
(
[0] => I am the third string.
[1] => Array
(
[0] => Array
(
[0] => uucps
[1] => 1
[2] => 1
)
[1] => Array
(
[0] => uuHz
[1] => 1
[2] => 2
)
[2] => Array
(
[0] => uuhertz
[1] => 1
[2] => 1
)
)
)
[2] => Array
(
[0] => I am the first string.
[1] => Array
(
[0] => Array
(
[0] => round
[1] => 1
[2] => 1
)
[1] => Array
(
[0] => rhythm
[1] => 1
[2] => 1
)
)
)
)