Group data from two 2d arrays by three columns and retaining the lowest value in another column within each group

Question

I have 2 multidimensional Arrays with Flightdates (Price, Date, Airline,..). I want to merge and remove duplicates that have the same date but I need to keep the cheaper one . I have always the same flight, but different prices.

$array1 = array(
[0] => Array
    (
        [price] => 191
        [date1] => 22-07-2016
        [date2] => 30-07-2016
        [airline] => Lufthansa
    )
[1] => Array
    (
        [price] => 80
        [date1] => 25-07-2016
        [date2] => 30-07-2016
        [airline] => Easyjet
    )
[2] => Array
    (
        [price] => 243
        [date1] => 10-08-2016
        [date2] => 36-08-2016
        [airline] => Airberlin
    )
);

$array2 = array(
[0] => Array
    (
        [price] => 230
        [date1] => 22-07-2016
        [date2] => 30-07-2016
        [airline] => Lufthansa
    )

[1] => Array
    (
        [price] => 80
        [date1] => 25-07-2016
        [date2] => 30-07-2016
        [airline] => Easyjet
    )

[2] => Array
    (
        [price] => 200
        [date1] => 10-08-2016
        [date2] => 36-08-2016
        [airline] => Airberlin
    )
);

Answer 1

Just loop through the first array and match the price in second array with respect to key of first array and push the values into into new array..

First Answer

<?php
$newArray = array();
foreach($array1 as $key =>$val)
{
    if($val['price'] <= $array2[$key]['price'])
    {
        $newArray[] = $val;
    }
    else
    {
        $newArray[] = $array2[$key];
    }
}
print_r($newArray);
?>

LIVE EXAMPLE: CLICK HERE

Second Answer

$newArray = array();
foreach($array1 as $key => $val)
{
    foreach($array2 as $k => $v)
    {
        if($val['date1'] == $v['date1'] && $val['date2'] == $v['date2'] && $val['airline'] ==  $v['airline'])
        {
            if($val['price'] <= $array2[$key]['price'])
            {
                $newArray[] = $val;
            }
            else
            {
                $newArray[] = $v;
            }
        }
    }
}
print_r($newArray);

LIVE EXAMPLE: CLICK HERE

This will give you:

Array
(
    [0] => Array
        (
            [price] => 191
            [date1] => 22-07-2016
            [date2] => 30-07-2016
            [airline] => Lufthansa
        )

    [1] => Array
        (
            [price] => 80
            [date1] => 22-07-2016
            [date2] => 30-07-2016
            [airline] => Easyjet
        )

    [2] => Array
        (
            [price] => 200
            [date1] => 22-07-2016
            [date2] => 30-07-2016
            [airline] => Airberlin
        )

)