如何按列值对子数组进行分组？

$arr = array();

foreach($old_arr as $key => $item)
{
   $arr[$item['id']][$key] = $item;
}

ksort($arr, SORT_NUMERIC);

for($i = 0 ; $i < count($arr)  ; $i++ )
{
    $tmpArr[$arr[$i]['id']] = $arr[$i]['id'];
}
$vmpArr = array_keys($tmpArr);
print_r($vmpArr);

在@baba的回答基础上，我想进一步扩展，但这会创建一个更复杂的三层多维数组（array（array（array）））：

$group = array();
 foreach ( $array as $value ) {
   $group[$value['id']][] = $value; 
 }

// output only data from id 96
foreach ($group as $key=>$value) { //outer loop
 foreach ($value as $k=>$v){ //inner loop
  if($key==96){ //if outer loop is equal to 96 (could be variable)
   for ($i=0;$i<count($k);$i++){ //iterate over the inner loop
        printf($key.' has a part no. of '.$v['part_no'].' and shipping no. of '.$v['shipping_no'].'<br>');
   }
 }
}
 }

将输出：

96具有零件号为reterty和运输号为212755-1

96具有零件号为dftgtryh和运输号为212755-1

function groupeByPHP($array,$indexUnique,$assoGroup,$keepInOne){
$retour = array();
$id = $array[0][$indexUnique];
foreach ($keepInOne as $keep){
    $retour[$id][$keep] = $array[0][$keep];
}
foreach ($assoGroup as $cle=>$arrayKey){
    $arrayGrouped = array();
        foreach ($array as $data){
            if($data[$indexUnique] != $id){
                $id = $data[$indexUnique];
                foreach ($keepInOne as $keep){
                    $retour[$id][$keep] = $data[$keep];
                }
            }
            foreach ($arrayKey as $val){
                $arrayGrouped[$val] = $data[$val];
            }
            $retour[$id][$cle][] = $arrayGrouped;
            $retour[$id][$cle] = array_unique($retour[$id][$cle],SORT_REGULAR);
        }
}
return  $retour;
}

groupeByPHP($yourArray,'id',array('desc'=>array('part_no','packaging_type')),array('id','shipping_no')) 

请检查Nspl中的indexed函数：

use function \nspl\a\indexed;
$grouped = indexed($data, 'id');

function array_group_by($arr, array $keys) {

if (!is_array($arr)) {
    trigger_error('array_group_by(): The first argument should be an array', E_USER_ERROR);
}
if (count($keys)==0) {
    trigger_error('array_group_by(): The Second argument Array can not be empty', E_USER_ERROR);
}

// Load the new array, splitting by the target key
$grouped = [];
foreach ($arr as $value) {
    $grouped[$value[$keys[0]]][] = $value;
}

// Recursively build a nested grouping if more parameters are supplied
// Each grouped array value is grouped according to the next sequential key
if (count($keys) > 1) {
        foreach ($grouped as $key => $value) {
       $parms = array_merge([$value], [array_slice($keys, 1,count($keys))]);
       $grouped[$key] = call_user_func_array('array_group_by', $parms);

    }
}
return $grouped;

}

$arr = array(
    '0' => array(
        'key0' => 'value0',
        'key1' => 'value1',
        'key2' => 'value02',
    ),
    '2' => array(
        'key0' => 'value0',
        'key1' => 'value1',
        'key2' => 'value12',
    ),
    '3' => array(
        'key0' => 'value0',
        'key1' => 'value3',
        'key2' => 'value22',
    ),
);
$keys = array('key0', 'key1', 'key2');

Output:

$arr = array(
    'value0' => array(
        'value1 => array(
            'value02' => null,
            'value12' => null,
        ),
        'value3' => 'value22',
    ),
);

Code:

function array_group_by_keys(&$arr, $keys) {

    if (count($arr) < 2){
        $arr = array_shift($arr[0]);
        return;
    }

    foreach ($arr as $k => $item) {
        $fvalue = array_shift($item);
        $arr[$fvalue][] = $item;
        unset($arr[$k]);
    }

    array_shift($keys);
    foreach ($arr as &$sub_arr) {
        array_group_by_keys($sub_arr, $keys);
    }
}

这应该是对关联数组进行分组的操作 例如按国家分组

function getGroupedArray($array, $keyFieldsToGroup) {   
    $newArray = array();

    foreach ($array as $record) 
        $newArray = getRecursiveArray($record, $keyFieldsToGroup, $newArray);

    return $newArray;
}
function getRecursiveArray($itemArray, $keys, $newArray) {
    if (count($keys) > 1) 
        $newArray[$itemArray[$keys[0]]] = getRecursiveArray($itemArray,    array_splice($keys, 1), $newArray[$itemArray[$keys[0]]]);
    else
        $newArray[$itemArray[$keys[0]]][] = $itemArray;

    return $newArray;
}

$countries = array(array('Country'=>'USA', 'State'=>'California'),
                   array('Country'=>'USA', 'State'=>'Alabama'),
                   array('Country'=>'BRA', 'State'=>'Sao Paulo'));

$grouped = getGroupedArray($countries, array('Country'));

当遇到唯一标识列值时，通过将引用变量推入结果数组中，您无需在分组后重新索引结果数组。

代码：（演示）

$result = [];
foreach ($array as $row) {
    $key = $row['id'];  // assign the grouping column's value
    unset($row['id']);  // remove the grouping column from the row
    if (!isset($ref[$key])) {
        $ref[$key] = [$row];      // declare first entry as a subarray
        $result[] = &$ref[$key];  // push the reference variable into the result array
    } else {
        $ref[$key][] = $row; // add a child to the reference
    }
}
var_export($result);

$result = array_combine(
    array_column($source, $groupByColumn),
    $source
);