Problem with looping and array merging in PHP

Question

I have two 2D arrays. They both contain id and other, not so-related, stuff. My job is to merge those two arrays together if id's match!

This is how they look:

array(3) {
  [0]=>
  array(3) {
    ["id"]=>
    string(3) "161"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
  }
  [1]=>
  array(3) {
    ["id"]=>
    string(3) "164"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
  [2]=>
  array(3) {
    ["id"]=>
    string(3) "168"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
}

array(2) {
  [0]=>
  array(3) {
    ["id"]=>
    string(3) "161"
    ["z"]=>
    string(1) "baz"
  }
  [1]=>
  array(3) {
    ["id"]=>
    string(3) "164"
    ["z"]=>
    string(1) "baz"
}

And this is how result should look:

array(3) {
  [0]=>
  array(3) {
    ["id"]=>
    string(3) "161"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    ["z"]=>
    string(1) "baz"
    }
  }
  [1]=>
  array(3) {
    ["id"]=>
    string(3) "164"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    ["z"]=>
    string(1) "baz"
    }
  [2]=>
  array(3) {
    ["id"]=>
    string(3) "168"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
}

And this is what I have so far. Of course, it doesn't work.

foreach ($rated_items as $item) {

    foreach ($posts as $post) {

        if ($post['id'] == $item['id']) {

            $posts = array_merge($posts, $item); // Doesn't work at all.

        }

    }

}

The problem is that I don't know how to merge current $post to current $item and then, both of them, add to $posts array without getting duplicates.

Thanks in an advice!

daGrevis · Accepted Answer · 2011-08-22 12:55:34Z

2

I don't know is this a bad tone, but I resolved my problem myself. :)

$i = 0;
foreach ($posts as $post) {

    $posts[$i] = $post;

    foreach ($rated_items as $item) {

        if ($post['id'] == $item['id']) {

            $posts[$i] += $item;

        }

    }

    ++$i;

}

Edit:

Even better way...

foreach ($posts as $key => $post) {

    if (isset($rated_items[$key])) {

        $posts[$key] += $rated_items[$key];

    }

}

edited Aug 22, 2011 at 12:55

answered Aug 22, 2011 at 6:51

daGrevis

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1 Comment

lepe Over a year ago

You don't need to use $i, you can use: foreach($posts as $key => &$post) instead. Also as recommendation use references (more efficient) like in: $posts[$i] =& $post;

lepe · Accepted Answer · 2011-08-22 06:49:00Z

1

One way to achieve it is if you first re-index your arrays, in a way that will look like:

array(3) {
  [161]=>
  array(3) {
    ["id"]=>
    string(3) "161"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
  }
  [164]=>
  array(3) {
    ["id"]=>
    string(3) "164"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
  [168]=>
  array(3) {
    ["id"]=>
    string(3) "168"
    ["x"]=>
    string(1) "foo"
    ["y"]=>
    string(1) "bar"
    }
}

Basically you will set as key of each array, your "id" value. Then you can array_merge() them without a problem.

I hope it helps you.

answered Aug 22, 2011 at 6:49

lepe

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Comments

Mihai Iorga · Accepted Answer · 2011-08-22 06:57:24Z

0

this should work:

$newArray = array();
foreach($array as $key => $arr){
    if(@$array2[$key]['id'] == $arr['id']){
        $newArray[] = array_merge($arr, $array2[$key]);
    } else {
        $newArray[] = $arr;
    }
}

answered Aug 22, 2011 at 6:57

Mihai Iorga

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Comments

Martin54 · Accepted Answer · 2023-06-27 08:02:21Z

0

$tmp = array_merge($posts, $rated_items);
$final = array();
foreach($tmp as $v) {
    foreach($v as $k => $va) {
        $final[$v['id']][$k] = $va; 
    }
}

or

$tmp = array_merge($posts, $rated_items);
$final = array();
foreach($tmp as $v) {
    if($final[$v['id']]) {
        $final[$v['id']] = array_merge($final[$v['id']], $v);
    } else {
        $final[$v['id']] = $v;
    }
}

edited Jun 27, 2023 at 8:02

Martin54

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answered Aug 22, 2011 at 7:07

Dubbo

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