Filter a 2d array by shared columns in another 2d array, then sum values in another column

Question

How can I filter a 2d array by the shared column values in another array then sum the values in another column of the filtered data set?

$hotel = [
    [
        'name' => 'hotel one',
        'hotel_price' => '100',
        'hotel_child_price' => '50'
    ],
    [
        'name' => 'hotel two',
        'hotel_price' => '200',
        'hotel_child_price' => '100'
    ],
    [
        'name' => 'hotel three',
        'hotel_price' => '300',
        'hotel_child_price' => '200'
    ],
];

$user_selected_hotel = [
    [
        'name' => 'hotel one',
        'hotel_price' => '100'
    ],
    [
        'name' => 'hotel three',
        'hotel_price' => '300'
    ]
];

How can I retrieve from the first array the hotel_child_price which the user has selected meaning the sum of 50 and 200 = 250.

The second array represents the user's hotel choice.

My current code:

foreach ( $user_selected_hotel as $lp => $hp) {
    $hotl_slct = $hp;
}

function searchForId($hotl_slct, $hotel) {
    foreach ($hotel as $cust1 => $cust_htl) {
        if ($cust_htl['name'] === $hotl_slct) {
            return $cust1;
        }
    }
    return null;
}

Please edit your question and include what you have tried that is not working as you expect it to. — Dave
– Dave, Commented Sep 16, 2019 at 17:44
How does that mean the user selected 200+50? I don't understand... — Andreas
– Andreas, Commented Sep 16, 2019 at 18:22

Vasilis G. · Accepted Answer · 2019-09-16 18:33:34Z

1

You can use array functions to easily achieve your desired result, without for loops:

// Get hotel prices.
$prices = array_column($user_selected_hotel, 'hotel_price');
// Find those records from $hotel whose hotel prices are in prices.
$resultPrices = array_filter($hotel, function($elem) use ($prices) { return in_array($elem['hotel_price'], $prices);});
// Sum them.
$finalResult = array_sum(array_column($resultPrices, 'hotel_child_price'));
// Print result.
echo $finalResult;

An even shorter answer (in lines of code):

$resultPrices = array_filter($hotel, function($elem) use ($user_selected_hotel) { return in_array($elem['hotel_price'], array_column($user_selected_hotel, 'hotel_price'));});
$finalResult = array_sum(array_column($resultPrices, 'hotel_child_price'));

Note: Some of your data are missing ,. Please consider correcting your sample data before running the above snippet.

edited Sep 16, 2019 at 18:33

answered Sep 16, 2019 at 18:22

Vasilis G.

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4 Comments

Nigel Ren Over a year ago

I've used the array functions a lot and they are very useful. But I've also realised they can often do a lot more work than is needed. For example using array_column() will extract the data from all rows, even if you only end up searching the first few.

Vasilis G. Over a year ago

@NigelRen thank you for your remark, I wasn't aware of the overhead that array_column causes. I will try to improve my answer. But the logic implemented is that first you need to extract all values from $hotel and then filter them according to the values of $user_selected_hotel in order to get the final prices and sum them.

Nigel Ren Over a year ago

It's not about improving your answer - the answer is fine, it's just about being aware of the code your using and what it does in the background.

Taher Over a year ago

And just like that, me banging my head for 2 days straight without sleeping have paid off, You sir have solved the dilemma,Thank you so much

Nigel Ren · Accepted Answer · 2019-09-16 18:21:54Z

1

I've corrected the source data (missing a few ,'s), but the main thing is about how to find each record.

I've changed the searchForId() method to search for the record (using a simple foreach() and when found, it returns the array element for that name. As it returns the array element, all it does then is to extract the 'hotel_child_price' value and add it to a running total.

$total = 0;
foreach( $user_selected_hotel as $lp => $hp) {
    $total += searchForID($hp['name'], $hotel)['hotel_child_price'];
}
echo $total;

function searchForId($hotl_slct, $hotels ) {
    foreach ( $hotels as $hotel )   {
        if ( $hotel['name'] == $hotl_slct ) {
            return $hotel;
        }
    }
    return null;
}

answered Sep 16, 2019 at 18:21

Nigel Ren

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Comments

Lucas Arbex · Accepted Answer · 2019-09-16 18:22:44Z

I don't think I fully understood what you want. But check if the following is what you are searching for, please:

$hotel = [
    [
        'name' => 'hotel one',
        'hotel_price' => '100',
        'hotel_child_price' => '50'
    ],
    [
        'name' => 'hotel two',
        'hotel_price' => '200',
        'hotel_child_price' => '100'
    ],
    [
        'name' => 'hotel three',
        'hotel_price' => '300',
        'hotel_child_price' => '200'
    ],
];

$user_selected_hotel = [
    [
        'name' => 'hotel one',
        'hotel_price' => '100'
    ],
    [
        'name' => 'hotel three',
        'hotel_price' => '300'
    ]
];

foreach($user_selected_hotel as $selected) {
    $key = array_search($selected['name'], array_column($hotel, 'name'));
    $merge = array_merge($selected, $hotel[$key]);
    $merge['hotel_price'] = $selected['hotel_price'] + $hotel[$key]['hotel_price'];
    return $merge;
}

The line $merge['hotel_price'] = $selected['hotel_price'] + $hotel[$key]['hotel_price']; represents the sum between both 'hotel_price', from $hotel and $user_selected_hotel arrays.

Let me know if this is what you want.

mickmackusa · Accepted Answer · 2023-10-21 21:33:29Z

Value-based filtering in a functional style: (Demo)

var_export(
    array_sum(
        array_column(
            array_uintersect(
                $hotel,
                $user_selected_hotel,
                fn($a, $b) => $a['name'] <=> $b['name']
            ),
            'hotel_child_price'
        )
    )
);

Key-based filtering in a functional style: (Demo)

var_export(
    array_sum(
        array_intersect_key(
            array_column($hotel, 'hotel_child_price', 'name'),
            array_column($user_selected_hotel, null, 'name')
        )
    )
);

Foreach loop with selective row destructuring and a lookup array: (Demo)

$lookup = array_column($hotel, 'hotel_child_price', 'name');
$sum = 0;
foreach ($user_selected_hotel as ['name' => $name]) {
    $sum += $lookup[$name];
}
var_export($sum);

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