PHP: How to break an associative array into a single array?

Question

How do I take an array like this:

Array 
( 
    [0] => Array 
    ( 
        [id] => 1 
        [BillGroup] => Group A 
    ) 
    [1] => Array 
    ( 
        [id] => 2 
        [BillGroup] => Group B 
    ) 
)

and dynamically turn it into an array like this:

$params = array('1' => 'Group A', '2' => 'Group B')

Where '1' and '2' is from [id] and 'Group 1' and 'Group 2' is from [BillGroup].

I need to be able to pass $params into Codeigniter's form_dropdown() helper function as the 2nd parameter to supply the dropdown options

Sometimes the solution to a question is even in a user profile, hint, hint (@abracadaver) — Rizier123
– Rizier123, Commented Mar 24, 2016 at 0:00

fusion3k · Accepted Answer · 2016-03-24 00:20:37Z

2

You can use array_column:

$params = array_column ( $array , 'BillGroup', 'id' );

Result:

Array
(
    [1] => Group A 
    [2] => Group B 
)

array_combine is available on PHP >= 5.5.0. On previous version you can use array_map:

$params = array();
array_map
(
    function ($row) use (&$params) 
    {
        $params[ $row['id'] ] = $row['BillGroup'];
    }
    ,$array
);

Note that we need to pass $params by reference due to variable scope inside anonymous function.

See more about array_column()
See more about array_map()

edited Mar 24, 2016 at 0:20

answered Mar 24, 2016 at 0:01

fusion3k

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4 Comments

Rizier123 Over a year ago

Why array_combine()? Totally not needed.

fusion3k Over a year ago

@Rizier123 to have 'id' values as keys

Rizier123 Over a year ago

I think looking at the manual page for array_column() would be worth it, hint

fusion3k Over a year ago

@Rizier123 Ok ok ok... I've forgotten and edited. Thank you

Giri Annamalai M · Accepted Answer · 2016-03-24 12:18:04Z

<?php
print "<pre>";
echo "Your Array:<br>";
    $array=array(

                array('id'=>1 , 'billgroup'=>'Group A'),
                array('id'=>2 , 'billgroup'=>'Group B'),
                array('id'=>3 , 'billgroup'=>'Group C')

        );

print_r($array);


function recursive($array, $level = 1){

    global $temp_data;

    foreach($array as $key => $value){
        //If $value is an array.
        if(is_array($value)){
            //We need to loop through it.
            recursive($value, $level + 1);
        } else{

            //It is not an array, so print it out.
            $temp_data[] = $value;                                      
            // echo $key . ": " . $value, '<br>';
        }
    }

    return $temp_data;
}

recursive($array);
// Converted Array
echo "Converted Array:<br>";

print_r($temp_data);

$i=0;$j=1;$len = count($temp_data)/2;

// Converting Normal Array into Associative
echo "Normal Array to Associative Array:<br>";
for($l=1;$l<=$len;$l++){

    $output[$temp_data[$i]]= $temp_data[$j];
    $i=$i+2; $j=$j+2;
}
print_r($output);

?>

OUTPUT:

Your Array:
Array
(
    [0] => Array
        (
            [id] => 1
            [billgroup] => Group A
        )

    [1] => Array
        (
            [id] => 2
            [billgroup] => Group B
        )

    [2] => Array
        (
            [id] => 3
            [billgroup] => Group C
        )

)
Converted Array:
Array
(
    [0] => 1
    [1] => Group A
    [2] => 2
    [3] => Group B
    [4] => 3
    [5] => Group C
)
Normal Array to Associative Array:
Array
(
    [1] => Group A
    [2] => Group B
    [3] => Group C
)

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