using one array to filter another array

Question

I was just wondering if php had built in functions to filter an array based on the key of another array?

array 1 - is a list of all users and their basic info

array 2 - contains a meeting schedule with the users id's

e.g.

array 1 [0]([user_id], [name], [age], [contact]), 
        [1]([user_id], [name], [age], [contact])
        etc.

array 2 [0]([user_id], [time], [date], [place])
        [1]([user_id], [time], [date], [place])

Is there a way to filter array 1 so that it only contains the rows that correspond to the [user_id] in array 2.

I understand that I could use loops and custom functions to achieve this however, I just wanted to see if there was a simple way.

Thanks

You mean like array_merge?

hjpotter92
– hjpotter92

2013-04-10 17:52:21 +00:00
Commented Apr 10, 2013 at 17:52 — hjpotter92
– hjpotter92, Commented Apr 10, 2013 at 17:52

Angelin Nadar · Accepted Answer · 2013-04-11 09:29:03Z

2

array_intersect_key($array1, $array2)

PHP Manual

code:

$array1 = array('user1'=> array('name'=>'name1','age' => 'age1'),
                'user2'=> array('name'=>'name2','age' => 'age2'),
                'user3'=> array('name'=>'name3','age' => 'age3'));

//array with key to search for
$array2 = array('user2'=> array('time'=>'time2','date' => 'date2'));     
echo '<pre>';
print_r(array_intersect_key($array1,$array2));
echo '</pre>';

o/p:

    Array
(
    [user2] => Array
        (
            [name] => name2
            [age] => age2
        )

)

edit:

Ah got your problem. If you want to manipulate your given array as per the above structure and then apply array_intersect_key(), you can do this:

function compare($key1,$key2){
    global $array1,$array2;

    if($array1[$key1]['userid'] == $array2[$key2]['userid'])
        return 0;
    if($array1[$key1]['userid'] > $array2[$key2]['userid'])
        return 1;
    else
        return -1;
}

$array1 = array(array('userid'=>'user1','name'=>'name1','age' => 'age1'),
                array('userid'=>'user2','name'=>'name2','age' => 'age2'),
                array('userid'=>'user3','name'=>'name3','age' => 'age3'));

//array with key to search for
$array2 = array(array('userid'=>'user2','time'=>'time2','date' => 'date2'));     

echo '<pre>';
print_r(array_intersect_ukey($array1,$array2,'compare'));
echo '</pre>';

o/p:
====
Array
(
    [1] => Array
        (
            [userid] => user2
            [name] => name2
            [age] => age2
        )

)

edited Apr 11, 2013 at 9:29

answered Apr 10, 2013 at 17:56

Angelin Nadar

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6 Comments

Rwd Over a year ago

is does seem to be working however, the [user_id] is off by one?!

Angelin Nadar Over a year ago

didnt get u? can u illustrate?

Rwd Over a year ago

the schedule [user_id]=24, the result from array_intersect_key showed [user_id]=23.

Rwd Over a year ago

It's because it's technically a multidimensional array, so it's using the index of the rows rather than the key [user_id].

Rwd Over a year ago

here's a link: link The first array is using array_insersect_key, the second is the main list, the third is the schedule that i want to use to filter the second array.

|

Rwd · Accepted Answer · 2018-06-11 22:40:32Z

1

I've decided it's much easier to just use 2 loops.

The first one to create an array of the [user_id]'s and the second one to use in_array like, so:

$user_id = array();
foreach($users as $id){
    $user_id[]= $id['user_id'];
}
$names = array();
foreach ($schedule as $name){
    if(in_array($name['id'], $user_id)) $names[] = $name;
}

Too simple to bother looking for a php function.

edited Jun 11, 2018 at 22:40

answered Apr 11, 2013 at 7:53

Rwd

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