PHP merges multiple arrays. The same element takes the intersection of different elements to form an array

php Merge multiple arrays Take the intersection of the same elements Different elements form an array
Brother Zha Published on 2014/01/23 22:00 read 3K+ Collection 4 answer 10
PHP
For help ：

The array format is like this ：

$arr=array(
array(‘element1’=>‘a’,‘element2’=>1),
array(‘element1’=>‘b’,‘element2’=>2),
array(‘element1’=>‘a’,‘element2’=>2),
array(‘element1’=>‘b’,‘element2’=>3),
);

Need to synthesize as ：

$arr=array(
array(‘element1’=>‘a’,‘element2’=>array(1,2)),
array(‘element1’=>‘b’,‘element2’=>array(2,3)),
);

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0
Brother Zha
Brother Zha 2014/01/23 22:50
$new=array();foreach($arr as $key => $value) {
$new[$value[‘element1’]][] = $value[‘element2’];
}
$new2=array();foreach($new as $k=>$v){
$new2[]=array{(}^{\prime }element{1}^{\prime }=>$k,‘element2’=>KaTeX parse error: Expected 'EOF', got '}' at position 5: v); }̲ print_r(new2);

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Wine free
Wine free 2014/01/24 08:39
Ask and answer ？
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Practicing typing
Practicing typing 2014/01/24 09:04
You are so efficient … One cycle is enough , direct k operation , Value merge array , Finished …
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Brother Zha
Brother Zha 2014/01/24 09:44
Reference from “cgf986916” The answer
You are so efficient … One cycle is enough , direct k operation , Value merge array , Finished …
For more efficient writing
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tretretre0000000000
tretretre0000000000 2014/01/24 10:18
$new_array = array();
$a=array();foreach($arr as $key => KaTeX parse error: Expected '}', got 'EOF' at end of input: …{ if(!in_array(val[‘element1’],$a)){
$a[] = $val[‘element1’];
$ne{w}_{a}rray[$val[‘element1’]] = $val;
}else{
$ne{w}_{a}rray[$val[‘element1’]][‘element2’] = array_merge(array($ne{w}_{a}rray[$val[‘element1’]][‘element2’]),array($val[‘element2’]));
}
}
$ne{w}_{a}rray=arra{y}_{v}alues($new_array);
In fact, one cycle can really . dedicated , try .

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Practicing typing
Practicing typing 2014/01/24 11:36
You have a good one , But it can improve
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List of Posts
List of Posts 2014/01/24 10:20
$arr=array(
array(‘element1’=>‘a’,‘element2’=>1),
array(‘element1’=>‘b’,‘element2’=>2),
array(‘element1’=>‘a’,‘element2’=>2),
array(‘element1’=>‘b’,‘element2’=>3),
);

class timer
{
private $start_time = NULL;
private $end_time = NULL;

private function getmicrotime()
{
  list($usec, $sec) = explode(" ", microtime());
  return ((float)$usec + (float)$sec);
}

function start()
{
  $this->start_time = $this->getmicrotime();
}

function stop()
{
  $this->end_time = $this->getmicrotime();
}

function result()
{
    if (is_null($this->start_time))
    {
        exit('Timer: start method not called !');
        return false;
    }
    else if (is_null($this->end_time))
    {
        exit('Timer: stop method not called !');
        return false;
    }

    return round(($this->end_time - $this->start_time), 4);
}

# an alias of result function
function time()
{
    $this->result();
}

}
// @pxv Methods 0.0343 second
$timer = new timer();
$timer->start();
$i=0;for($i = 0; $i<10000; $i++){
$new_array = array();
$a=array();foreach($arr as $key => KaTeX parse error: Expected '}', got 'EOF' at end of input: …{ if(!in_array(val[‘element1’],$a)){
$a[] = $val[‘element1’];
$ne{w}_{a}rray[$val[‘element1’]] = $val;
}else{
$ne{w}_{a}rray[$val[‘element1’]][‘element2’] = array_merge(array($ne{w}_{a}rray[$val[‘element1’]][‘element2’]),array($val[‘element2’]));
}
}
$ne{w}_{a}rray=arra{y}_{v}alues($new_array);
}

$timer->stop();
echo $timer->result();

echo ‘|’;

// My method 0.0522 second
$timer = new timer();
$timer->start();
$i=0;for($i = 0; $i<10000; $i++){
$arrCheck=arra{y}_{u}nique(arra{y}_{m}ap(function($subArr){return $subArr[‘element1’];}, $arr));
$arrResult=array();foreach($arrCheck as $name){
$tmp=array();foreach($arr as KaTeX parse error: Expected '}', got 'EOF' at end of input: …r){ if(subArr[‘element1’] == $name){
$tmp[] = KaTeX parse error: Expected 'EOF', got '}' at position 29: …nt2']; }̲ } arra…arrResult, array(‘element1’ => $name, ‘element2’ => KaTeX parse error: Expected 'EOF', got '}' at position 8: tmp)); }̲ //var_dump(arrResult);
}
$timer->stop();
echo $timer->result();

echo ‘|’;

// Brother monkey's method 0.0164 second
$timer = new timer();
$timer->start();
$i=0;for($i = 0; $i<10000; $i++){
$new=array();foreach($arr as $key => $value) {
$new[$value[‘element1’]][] = $value[‘element2’];
}
$new2=array();foreach($new as $k=>$v){
$new2[]=array{(}^{\prime }element{1}^{\prime }=>$k,‘element2’=>KaTeX parse error: Expected 'EOF', got '}' at position 5: v); }̲ //print_r(new2);
}
$timer->stop();
echo $timer->result();

Practicing typing 2014/01/24 11:38
Reference from “pxv” The answer
$new_array = array();
$a=array();foreach($arr as $key => KaTeX parse error: Expected '}', got 'EOF' at end of input: …{ if(!in_array(val[‘element1’],$a)){
$a[] = $val[‘element1’];
$ne{w}_{a}rray[$val[‘element1’]] = $val;
}else{
$ne{w}_{a}rray[$val[‘element1’]][‘element2’] = array_merge(array($ne{w}_{a}rray[$val[‘element1’]][‘element2’]),array($val[‘element2’]));
}
}
$ne{w}_{a}rray=arra{y}_{v}alues($new_array);
In fact, one cycle can really . dedicated , try .

$ne{w}_{a}rray=array();foreach($arr as $key => KaTeX parse error: Expected '}', got 'EOF' at end of input: … isset(new_array[$val[‘element1’]])
? $ne{w}_{a}rray[$val[‘element1’]][‘element2’] = array_merge(array($ne{w}_{a}rray[$val[‘element1’]][‘element2’]), array($val[‘element2’]))
: $ne{w}_{a}rray[$val[‘element1’]] = $val;
}
$ne{w}_{a}rray=arra{y}_{v}alues($new_array);

https://www.oschina.net/question/244077_142022