使用随机组排序按组对关联数组进行排序

Question

我有一个表示组的关联数组键/值。我想对数组进行洗牌，以便组按随机顺序排列，但组中的项目仅在其组中随机排列。换句话说，我想采取这样的东西：

[
[
"name" => "Buffy",
"group" => 1
],
[
"name" => "Willow",
"group" => 1
],
[
"name" => "Xander",
"group" => 2
],
[
"name" => "Giles",
"group" => 2
],
[
"name" => "Tara",
"group" => 3
],
[
"name" => "Angel",
"group" => 3
],
[
"name" => "Spike",
"group" => 3
]
]

并返回更像这样的东西：

[
[
"name" => "Spike",
"group" => 3
]
[
"name" => "Angel",
"group" => 3
],
[
"name" => "Tara",
"group" => 3
],
[
"name" => "Willow",
"group" => 1
],
[
"name" => "Buffy",
"group" => 1
],
[
"name" => "Xander",
"group" => 2
],
[
"name" => "Giles",
"group" => 2
],
]

我意识到这可能可以通过两种或三种类型来实现，但如果可以用一个usort来完成，那就太好了。

Answer 1

基本上，我的解决方案打乱输入数组，临时重组输入数组以收集具有相同group值的子数组，然后将数据返回到其原始结构。

代码：(演示(

shuffle($data);                         // randomize all subarrays
foreach ($data as $set) {
$grouped[$set['group']][] = $set;   // merge subarrays on group value
}
$output = [];
foreach($grouped as $group) {
array_push($output, ...$group);     // return to original array structure
}
var_export($output);

*请注意，...(splat 运算符(允许array_push()单独存储所有子数组(在每个组中(以生成原始结构。

可能的输出：

array (
0 => 
array (
'name' => 'Xander',
'group' => 2,
),
1 => 
array (
'name' => 'Giles',
'group' => 2,
),
2 => 
array (
'name' => 'Willow',
'group' => 1,
),
3 => 
array (
'name' => 'Buffy',
'group' => 1,
),
4 => 
array (
'name' => 'Spike',
'group' => 3,
),
5 => 
array (
'name' => 'Tara',
'group' => 3,
),
6 => 
array (
'name' => 'Angel',
'group' => 3,
),
)

Answer 2

试试...

$groups = [];
foreach (array_unique(array_column($myar, 'group')) as $k) $groups[$k] = rand();
foreach (array_keys($myar) as $k) $myar[$k]['rnd'] = rand();
usort($myar, function($a, $b) use ($groups) {
if ($gdif = $groups[$b['group']] - $groups[$a['group']]) return $gdif;
return $b['rnd'] - $a['rnd'];
});
foreach (array_keys($myar) as $k) unset($myar[$k]['rnd']);
print_r($myar);

使用您的数据运行，这是一个结果...

Array
(
[0] => Array
(
[name] => Buffy
[group] => 1
)
[1] => Array
(
[name] => Willow
[group] => 1
)
[2] => Array
(
[name] => Angel
[group] => 3
)
[3] => Array
(
[name] => Tara
[group] => 3
)
[4] => Array
(
[name] => Spike
[group] => 3
)
[5] => Array
(
[name] => Giles
[group] => 2
)
[6] => Array
(
[name] => Xander
[group] => 2
)
)