Php: arrays nested loop performance

Question

I have two arrays

$list = Array
([0] => stdClass Object
    (
        [id] => 10
        [data] => "test data"
    )
[1] => stdClass Object
...
...(max 3000 ~ 4000 items)

and

$attributes = Array
([0] => stdClass Object
    (
        [ids] => 11
        [list] => '<ul>...</ul>'
    )
[1] => stdClass Object
...
...(max 3000 ~ 4000 items)

I am trying to left join them but the only performing way I am being able to write for this to be usable is

$nrrowslist = count($list);
for ($i = 0; $i < $nrrowslist; $i++){
  $nrat = count($attributes);
  for ($j = 0; $j < $nrat; $j++)
  {
    if($list[$i]->id == $attributes[$j]->ids){
      $list[$i]->attributes = $attributes[$j]->list;
      array_splice($attributes, $j, 1); // remove the item
      break; // since there is other item with that id 
    }
  }
}

// completes in ~0.470 seconds

But if I write it

foreach($list as $art){
  foreach($attributes as $attr){
    if($art->id == $attr->ids){
      $art->attributes = $attr->list;           
    }
  }
}

it completes in ~ 5.500 seconds.. and is too much

what can I do to perform even more the first method situation?

Scuzzy · Accepted Answer · 2015-12-26 12:39:06Z

1

You may have some success with two iterations and using the common parameter in your assignment

$newlist = array();

// I'm sure there's a better way to do this initial assignment
foreach($list as $row)
{
  $newlist[$row->id] = $row;
}

foreach($attributes as $attr)
{
  if(isset($newlist[$attr->ids]) === true)
  {
    $newlist[$attr->ids]->attributes = $attr->list;
  }
}

var_dump($newlist);

answered Dec 26, 2015 at 12:39

Scuzzy

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1 Comment

daniel Over a year ago

It runs faster. Thank you! (~ 0.280 second)

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