Modifying multidimensional array in PHP replacing keys as the values [duplicate]

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 · Accepted Answer · 2016-05-29 03:45:47Z

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, 2016 at 3:45

answered May 29, 2016 at 2:58

badandyomega

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2 Comments

susanmanchester Over a year ago

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' ),

badandyomega Over a year ago

@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); } }

susanmanchester · Accepted Answer · 2016-05-29 03:12:28Z

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, 2016 at 3:12

susanmanchester

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1 Comment

user5051310 Over a year ago

You should edit this into your original question; don't make answers.

susanmanchester · Accepted Answer · 2016-05-29 03:15:33Z

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, 2016 at 3:15

susanmanchester

54 bronze badges

Comments

Konstantinos Vytiniotis · Accepted Answer · 2016-05-29 03:29:15Z

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.

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