Modifying multidimensional array in PHP replacing keys as the values

Question

How would you modify the following code using only a foreach loop by replacing the keys as the values? For examples the salad, chicken, and pancakes keys would the values instead.

$meals = array(
    'Lunch' => array(
            'salad' => 'italian',
            'salad2' => 'ranch',
            'salad3' => 'sesame',
            'salad4' => 'bluecheese'
        ), 

    'Dinner' => array(
            'chicken' => 'grilled',
            'chicken2' => 'baked',
            'chicken3' => 'steamed',
            'chicken4' => 'fried',
            'chicken5' => 'broiled'
        ), 

    'Breakfast' => array(
        'pancakes' => 'blueberry',
        'pancakes2' => 'cherry',
        'pancakes3' => 'strawberry',
        'pancakes4' => 'lemon'
        )
);

$newkey = array();

foreach($meals as $key => $value) {
    unset($value);
    // foreach ($)...
}


print_r($meals);

badandyomega · Answer 1 · 2016-05-29T03:45:47.537

1

Edit

If you're unable to use array_flip(), then you'll need to do two loops: one for each meal, and one for each meal option.

Example:

foreach ($meals as $meal => $mealOptions)
{
    $revisedMealOptions = array();

    foreach ($mealOptions as $originalKey => $newKey)
    {
        $revisedMealOptions[$newKey] = $originalKey;
    }

    $meals[$meal] = $revisedMealOptions;
}

Original Answer

It's not entirely clear what you're after. If all you want is to turn:

'Lunch' => array(
    'salad' => 'italian'
);

into

'Lunch' => array(
    'italian' => 'salad'
);

use array_flip().

Example:

$meals['Lunch'] = array_flip($meals['Lunch']);

See http://php.net/manual/en/function.array-flip.php.

edited May 29 '16 at 03:45

answered May 29 '16 at 02:58

badandyomega

252
1
4

what if you had two values that were the same? For example, 'salad' and 'salad2' both have values 'italian.' How would you ensure these still get printed out? $meals = array( 'Lunch' => array( 'salad' => 'italian', 'salad2' => 'italian', 'salad3' => 'sesame', 'salad4' => 'bluecheese' ), – susanmanchester May 29 '16 at 04:39
@susanmanchester if you have two values for the same key, you'll need to find an alternative structure, since array keys are unique. The easiest way is to use `isset` or `array_key_exists` to determine if the key you're trying to provide a value for exists, and if it does, store each value inside another internal array. Something like `if (isset($revisedMealOptions[$newKey])) { if (is_array($revisedMealOptions[$newKey])) { $revisedMealOptions[$newKey][] = $originalKey; } else { $revisedMealOptions[$newKey] = array($revisedMealOptions[$newKey], $originalKey); } }` – badandyomega May 29 '16 at 04:47

score 0 · Answer 2 · answered May 29 '16 at 03:12

0

I'm sorry I am a total beginner. I need to use a nested $foreach loop to address this question. For class I'm not allowed to use the array_flip function. I have tried

$newkey = array();

foreach($meals as $key => $value) {
  $newkey[] = $value; 
     foreach ($value as ){
    }
  }

answered May 29 '16 at 03:12

susanmanchester

5
4

1

You should edit this into your original question; don't make answers. – May 29 '16 at 03:29

score 0 · Answer 3 · answered May 29 '16 at 03:15

0

So, it would read:

Basically I need it to read:

Array(

[Lunch] => array(
        [italian] => salad,
        [ranch] => salad2,
        [sesame] => salad3,
        [bluecheese] => salad4
    )
 )

answered May 29 '16 at 03:15

susanmanchester

5
4

score 0 · Answer 4 · answered May 29 '16 at 03:29

The easiest way to do it would be like this:

$meals = array(
    'Lunch' => array(
        'salad' => 'italian',
        'salad2' => 'ranch',
        'salad3' => 'sesame',
        'salad4' => 'bluecheese'
    ),

    'Dinner' => array(
        'chicken' => 'grilled',
        'chicken2' => 'baked',
        'chicken3' => 'steamed',
        'chicken4' => 'fried',
        'chicken5' => 'broiled'
    ),

    'Breakfast' => array(
        'pancakes' => 'blueberry',
        'pancakes2' => 'cherry',
        'pancakes3' => 'strawberry',
        'pancakes4' => 'lemon'
    )
);

$newArray = array();

foreach ($meals as $key => $value) {
    $temp = array();
    foreach ($value as $innerKey => $innerValue) {
        $temp[$innerValue] = $innerKey;
    }
    $newArray[$key] = $temp;
}

unset($meals);

Basically, you create a new array and build it from the beginning with the use of the array $meals.

Modifying multidimensional array in PHP replacing keys as the values

4 Answers4