php - 如何在PHP中按最大相同值对数组进行排序

Question

如何按最大相同值对数组进行排序？？

这里是数组

Array
(
    [0] => 2
    [1] => 2
    [2] => 2
    [3] => 3
    [4] => 3
    [5] => 4
    [6] => 4
    [7] => 4
    [8] => 4
    [9] => 4
    [10] => 5
)

我想要的是按最大值对数组进行排序，所以数组应该看起来

Array
(   
    [0] => 4
    [1] => 4
    [2] => 4
    [3] => 4
    [4] => 4
    [5] => 2
    [6] => 2
    [7] => 2
    [8] => 3
    [9] => 3
    [10] => 5
)

Answer 1

试试这个:

$arr = [3,4,2,3,2,2,3,4,5,2];

$count = [];
foreach ($arr as $a)
{
  // Count how many times each number appears and store it in an array
  // where the key is the number and the value the count.
  $count[$a] = isset($count[$a]) ? $count[$a]+1 : 1;
}

// As @drip wrote you can use 'array_count_values' instead:
// $count = array_count_values($arr);

// Sort the array in reverse order while maintaining index association.
arsort($count);

$new = [];
foreach ($count as $a => $c)
{
  // Create a new array with the values appearing as many times as counted.
  for ($i = 0; $i < $c; $i++)
  {
    $new[] = $a;
  }
}