Get the key of the array with the lowest or highest value inside of a multidimensional array

lowest_highest_multidimensional_value.php

<?php
$arr = array(
  array(
    'id'      => 123,
    'amount'  => 39
  ),
  array(
    'id'      => 789,
    'amount'  => 27
  ),
  array(
    'id'      => 364,
    'amount'  => 15
  ),
  array(
    'id'      => 696,
    'amount'  => 22
  )
);

$amounts = array_column($arr, 'amount');

$lowest_count_key = array_search(min($amounts), $amounts, true);
// => 2

$lowest_count = $arr[$lowest_count_key];
// => array('id' => 364, 'amount' => 15);

$highest_count_key = array_search(max($amounts), $amounts, true);
// => 0

$highest_count = $arr[$highest_count_key];
// => array('id' => 123, 'amount' => 39);
?>