PHP multi-dimentional array merge

Question

I have 3 sets of array's that have been returned back from an API ($array1,$array2,$array3)

I need to combine these into 1 object with the highest price value for Ground, 2nd Day, Overnight.

$obj['ground'] should equal 3.15
$obj['2 Day'] should equal 19.29
$obj['Overnight'] should equal 29.26

arr1

Array
(
    [0] => Array
        (
            [Title] => Ground
            [Price] => 3.15
        )

    [1] => Array
        (
            [Title] => 2 Day
            [Price] => 12.11
        )

    [2] => Array
        (
            [Title] => 1 Day
            [Price] => 29.26
        )

)

arr2

Array
(
    [0] => Array
        (
            [Title] => Ground
            [Price] => 3.15
        )

    [1] => Array
        (
            [Title] => 2 Day
            [Price] => 19.29
        )

    [2] => Array
        (
            [Title] => 1 Day
            [Price] => 25.89
        )

)

arr3

Array
(
    [0] => Array
        (
            [Title] => Ground
            [Price] => 3.15
        )

    [1] => Array
        (
            [Title] => 2 Day
            [Price] => 16.29
        )

    [2] => Array
        (
            [Title] => 1 Day
            [Price] => 25.89
        )

)

What's the best way of doing this?

I think it’s best to do it by hand; just do what you need to do for it, without relying to those dummy PHP functions. array_merge is useful inside the loop. — Smar
– Smar, Commented Jan 25, 2016 at 8:01

Michael · Accepted Answer · 2016-01-26 13:14:21Z

2

A different approach. More functional, simpler and less error prone.

// Prepare result
$result = array_fill_keys([ 'ground', '2 Day', '1 Day' ], 0.0);

// Find the highest price and keep it in the result
$result = array_reduce(array_merge($array1, $array2, $array3), function ($result, $item) {
    if ($item['Price'] > $result[$item['Title']]) {
        $result[$item['Title']] = $item['Price'];
    }
    return $result;
}, $result);

print_r($result);

Outputs:

Array
(
    [ground] => 3.15
    [2 Day] => 19.29
    [1 Day] => 29.26
)

The good thing about this approach is that it relies on built-in functions and that can easily be extended to more titles and more arrays.

edited Jan 26, 2016 at 13:14

answered Jan 25, 2016 at 8:37

Michael

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Comments

Rajesh Kumar · Accepted Answer · 2016-01-25 07:58:23Z

2

        $array1 = array(
        array("Title"=>"ground", "Price"=>3.15),
        array("Title"=>"2 Day", "Price"=>12.11),
        array("Title"=>"1 Day", "Price"=>29.26)
        );
    $array2 = array(
        array("Title"=>"ground", "Price"=>3.15),
        array("Title"=>"2 Day", "Price"=>19.29),
        array("Title"=>"1 Day", "Price"=>25.89)
    );
    $array3 = array(
        array("Title"=>"ground", "Price"=>3.15),
        array("Title"=>"2 Day", "Price"=>16.29),
        array("Title"=>"1 Day", "Price"=>25.89)
    );
    $obj = new stdClass(); /** you asked object. */
    $size = count($array1);
/** Loops runs three time, `ground`, `2 Day` and `1 Day` will be sorted respectively in each iteration */
    for ($i = 0; $i<$size; $i++) {
        $maxValue = max(array($array1[$i]["Price"], $array2[$i]["Price"], $array3[$i]["Price"]));
        switch ($array1[$i]["Title"]) {
            case "ground": $obj->ground = $maxValue;
                break;
            /** '2 day' is not possible since object properties can not contain space. */
            case "2 Day": $obj->twoDay = $maxValue;
                break;
            case "1 Day": $obj->overNight = $maxValue;
                break;
        }
    }
    var_dump($obj);

answered Jan 25, 2016 at 7:58

Rajesh Kumar

937 bronze badges

3 Comments

Brad Over a year ago

Do you know how to make this work with out a preset number of arrays. (Where it could have 2 or 2000).

Rajesh Kumar Over a year ago

Can you please specify the input. ? than i could try :)

Michael Over a year ago

@RajeshKumar Consider using simpler approach to avoid errors (see my answer)

devpro · Accepted Answer · 2016-01-25 08:06:43Z

0

You can your required result as:

<?
// Your test array 1
$arr1[] = array('Title'=>'Ground','Price'=>'3.15');
$arr1[] = array('Title'=>'2 Day','Price'=>'12.11');
$arr1[] = array('Title'=>'1 Day','Price'=>'29.26');

foreach ($arr1 as $key => $value) {
    $newArr[$value['Title']] = $value['Price'];    
}

echo "<pre>";
print_r($newArr); // result of array1, you can follow this for other arrays as well
?>

Result:

Array
(
    [Ground] => 3.15
    [2 Day] => 12.11
    [1 Day] => 29.26
)

UPDATE 1:

<?
$arr1[] = array('Title'=>'Ground','Price'=>'3.15');
$arr1[] = array('Title'=>'2 Day','Price'=>'12.11');
$arr1[] = array('Title'=>'1 Day','Price'=>'29.26');

$arr2[] = array('Title'=>'Ground','Price'=>'3.15');
$arr2[] = array('Title'=>'2 Day','Price'=>'19.29');
$arr2[] = array('Title'=>'1 Day','Price'=>'25.89');

$arr3[] = array('Title'=>'Ground','Price'=>'3.15');
$arr3[] = array('Title'=>'2 Day','Price'=>'16.29');
$arr3[] = array('Title'=>'1 Day','Price'=>'25.89');

$customArr = array();
foreach ($arr1 as $key => $value) {
    $customArr[$key][$value['Title']][] = $value['Price'];    
}

foreach ($arr2 as $key => $value) {
    $customArr[$key][$value['Title']][] = $value['Price'];    
}

foreach ($arr3 as $key => $value) {
    $customArr[$key][$value['Title']][] = $value['Price'];    
}

$finalArr = array();
foreach ($customArr as $key => $value) {

    if(isset($value['Ground']))
        $finalArr['Ground'] = max($value['Ground']);

    if(isset($value['2 Day']))
        $finalArr['2 Day'] = max($value['2 Day']);

    if(isset($value['1 Day']))
        $finalArr['1 Day'] = max($value['1 Day']);
}

echo "<pre>";
print_r($finalArr);    

?>

Result:

Array
(
    [Ground] => 3.15
    [2 Day] => 19.29
    [1 Day] => 29.26
)

edited Jan 25, 2016 at 8:06

answered Jan 25, 2016 at 7:30

devpro

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4 Comments

Brad Over a year ago

What about arr2, arr3?

devpro Over a year ago

if other 2 is separate as arr1, than u can follow same process.. @Brad

devpro Over a year ago

Alright, these are seperate? and can u add the expected result in question.. @Brad

Brad Over a year ago

There are 3 sets off arrays. It's from 3 seperate API calls. I need to find the most expensive of the 3 as I show in the example. The example merges the data from all 3 calls into 1. 2nd day from the 2nd one, and 1 day from the 1st one.

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