基于元素依赖的PHP Order数组 [英] PHP Order array based on elements dependency

问题描述

相当困难的一个解释，但实际上我有一系列具有ID的项目，其中可以包含其他数组项目的ID列表。例如

  $ items = [
 [id：'one'，deps：['three']] 
 [id：'two']，
 [id：'three'，deps：['four'，'two']]，
 [id：'four'] 
]; 
  

所以你可以看到这里，一个取决于三个，三个取决于四和二。 / p>

我需要获得一个新的数组，它们按顺序包含这些项目，以便依次列出。所以上面的数组将转换成

  $ items = [
 [id：'four']，
 [id：'two']，
 [id：'three'，deps：['four'，'two']]，
 [id：'one'，deps：['three' ]] 
]; 
  

我该如何完成？我已经尝试过各种while循环检查项目位置，但不能破解。

谢谢

更新有些人表示重复的问题

解决方案

您可以使用这样的函数，它会遍历所有依赖关系，否则可以解决更多依赖关系：

  $ items = array（array（'id'=>'one'，'deps'=> array（'three'）），
 array（'id'=>两个'），
数组（'id'=>'三'，'deps'=>数组（'四'，'二'）），
数组（'id'=> '四'））; 
 
 
 $ sortedItems = sortDeps（$ items）; 
 var_dump（$ sortedItems）; 
 
函数sortDeps（$ items）{
 $ res = array（）; 
 $ doneList = array（）; 
 
 //而不是所有的项目都解决了：
 while（count（$ items）> count（$ res））{
 $ doneSomething = false; 
 
 foreach（$ items as $ itemIndex => $ item）{
 if（isset（$ doneList [$ item ['id']]））{
 //已经在结果集中的项目
继续; 
} 
 $ resolved = true; 
 
 if（isset（$ item ['deps']））{
 foreach（$ item ['deps'] as $ dep）{
 if（！isset（$ doneList [$ dep]））{
 //有不符合的依赖项：
 $ resolved = false; 
 break; 
} 
} 
} 
 if（$ resolved）{
 //满足所有依赖关系：
 $ doneList [$ item ['id'] ] = true; 
 $ res [] = $ item; 
 $ doneSomething = true; 
} 
} 
 if（！$ doneSomething）{
 echo'unresolvable dependency'; 
} 
} 
 return $ res; 
} 
  

Fairly hard one to explain, but effectively I've got an array of items which have IDs, of which can contain a list of IDs for other array items. for example

$items = [
   [id: 'one', deps: ['three']],
   [id: 'two'],
   [id: 'three', deps: ['four', 'two']],
   [id: 'four']
];

So as you can see here, one depends on three, and three depends on four and two.

I need to get a new array, that contains these items in order - so that the dependencies are listed in order. So the above array would convert into

$items = [
   [id: 'four'],
   [id: 'two'],
   [id: 'three', deps: ['four', 'two']],
   [id: 'one', deps: ['three']]
];

How would I complete this? I've tried various while loops checking for item positions, but can't crack it.

Thanks

UPDATE Some people have said its a duplicate question of THIS but the main difference being the above example has multiple dependencies - whereas the mentioned thread only works on a single string dependency

解决方案

you can use a function like this, that iterates until all dependencies are met, or no more dependencies can be resolved:

$items = array(array('id' => 'one', 'deps' => array('three')),
                array('id' => 'two'),
                array('id' => 'three', 'deps' => array('four', 'two')),
                array('id' =>'four'));


$sortedItems = sortDeps($items);
var_dump($sortedItems);

function sortDeps($items) {
    $res = array();
    $doneList = array();

    // while not all items are resolved:
    while(count($items) > count($res)) {
        $doneSomething = false;

        foreach($items as $itemIndex => $item) {
            if(isset($doneList[$item['id']])) {
                // item already in resultset
                continue;
            }
            $resolved = true;

            if(isset($item['deps'])) {
                foreach($item['deps'] as $dep) {
                    if(!isset($doneList[$dep])) {
                        // there is a dependency that is not met:
                        $resolved = false;
                        break;
                    }
                }
            }
            if($resolved) {
                //all dependencies are met:
                $doneList[$item['id']] = true;
                $res[] = $item;
                $doneSomething = true;
            }
        }
        if(!$doneSomething) {
            echo 'unresolvable dependency';
        }
    }
    return $res;
}

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