Using nested loops, populate a 2d array with associative first level keys and indexed row elements from two flat arrays

Question

I am trying to create a multidimensional array in PHP using a foreach loop. Here is the code thus far:

$levels = array('low', 'medium', 'high');
$attributes = array('fat', 'quantity', 'ratio', 'label');
 
foreach ($levels as $key => $level):
    foreach ($attributes as $k =>$attribute):
        $variables[] = $attribute . '_' . $level;
    endforeach;
endforeach;

echo '<pre>' . print_r($levels,1) . '</pre>';   
echo '<pre>' . print_r($variables,1) . '</pre>';

The output from this code is a single dimension array; however, that is not the intent. The desired array should look like this:

OutputGoal

How should the code be modified to achieve the goal?

Are you trying to combine two arrays into a single array, or create a new array from the data in those two arrays? — Lance
– Lance, Commented Aug 8, 2013 at 20:42

JimL · Accepted Answer · 2013-08-08 20:42:38Z

16

You're aaalmost there. Just add the level to the array creation :)

$levels = array('low', 'medium', 'high');
$attributes = array('fat', 'quantity', 'ratio', 'label');

foreach ($levels as $key => $level):
       foreach ($attributes as $k =>$attribute):
             $variables[$level][] = $attribute . '_' . $level; // changed $variables[] to $variables[$level][]
       endforeach;
endforeach;

echo '<pre>' . print_r($levels,1) . '</pre>';   
echo '<pre>' . print_r($variables,1) . '</pre>';

Output

Array
(
    [low] => Array
        (
            [0] => fat_low
            [1] => quantity_low
            [2] => ratio_low
            [3] => label_low
        )

    [medium] => Array
        (
            [0] => fat_medium
            [1] => quantity_medium
            [2] => ratio_medium
            [3] => label_medium
        )

    [high] => Array
        (
            [0] => fat_high
            [1] => quantity_high
            [2] => ratio_high
            [3] => label_high
        )

)

answered Aug 8, 2013 at 20:42

JimL

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1 Comment

user1551496 Over a year ago

I have this problem. I need someting like that out of a foreach.

$arrOptions = array(  array(                   'value' => 'value1',                    'label' =>  'label1'               ) );

Foreach value and label is the same variable. What i try is

$arrOptions = array(); 			foreach($daterange as $option) { 			 	 	$arrOptions[value] = $option->format; 			  		$arrOptions[label] = $option->format; 				}

Tomasz Kowalczyk · Accepted Answer · 2020-06-23 12:06:14Z

6

$levels = ['low', 'medium', 'high'];
$attributes = ['fat', 'quantity', 'ratio', 'label'];

$result = [];
foreach ($levels as $level) {
    $result[$level] = [];
    foreach ($attributes as $attribute) {
        $result[$level][] = $attribute . '_' . $level;
    }
}

var_dump($result);

edited Jun 23, 2020 at 12:06

answered Aug 8, 2013 at 20:44

Tomasz Kowalczyk

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4 Comments

mickmackusa Over a year ago

If you are editing, this code-only answer is missing its educational explanation.

Tomasz Kowalczyk Over a year ago

I reformatted code in my own seven-years-old answer. I don't have anything to add. :)

mickmackusa Over a year ago

You could explain how the OP's code was failing and/or how your code manages to produce the expected output structure.

dimButTries Over a year ago

@TomaszKowalczyk thank you for supplying this answer; it got me out of a coding nadir converting a multi-dimensional array to CSV.

mickmackusa · Accepted Answer · 2024-02-01 10:37:01Z

1

$levels = ['low', 'medium', 'high'];
$attributes = ['fat', 'quantity', 'ratio', 'label'];

foreach ($levels as $level) {
    foreach ($attributes as $attribute) {
        $variables[$level][] = $attribute . '_' . $level;
   }
}

print_r($variables);

http://codepad.viper-7.com/xlvZ2W

edited Feb 1, 2024 at 10:37

mickmackusa♦

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answered Aug 8, 2013 at 20:46

user557846

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