unique array on base on value of specific key - php

Question

I have the following array:
Array
(
[0] => Array
(
[hotelID] => 10
[hotelcategoryID] => 12
[hotelName] => Grand Forest Metsovo
[hotelShortDescription] =>
[hotelVisible] => 1
[roomID] => 2
)
[1] => Array
(
[hotelID] => 10
[hotelcategoryID] => 12
[hotelName] => Grand Forest Metsovo
[hotelShortDescription] =>
[hotelVisible] => 1
[roomID] => 3
)
[2] => Array
(
[hotelID] => 10
[hotelcategoryID] => 12
[hotelName] => Grand Forest Metsovo
[hotelShortDescription] =>
[hotelVisible] => 1
[roomID] => 4
)
[3] => Array
(
[hotelID] => 14
[hotelcategoryID] => 7
[hotelName] => Hotel Metropolis
[hotelShortDescription] =>
[hotelVisible] => 1
[roomID] => 23
)
[4] => Array
(
[hotelID] => 14
[hotelcategoryID] => 7
[hotelName] => Hotel Metropolis
[hotelShortDescription] =>
[hotelVisible] => 1
[roomID] => 24
)
)
I have two different hotelID keys. I would like to extract only one element (the first one) where the hotelID is unique in whole array. I am trying with following code:
$data['uniqueHotels'] = array_map('unserialize', array_unique(array_map('serialize', $hotels)));
but without any luck so far.
Anyone can give me a hint?

Answer 1

If looking for the first element:
<?php
$hotels = array(
array(
'id' => 1,
'hotelID' => 10
),
array(
'id' => 2,
'hotelID' => 10,
),
array(
'id' => 3,
'hotelID' => 20,
),
array(
'id' => 4,
'hotelID' => 20,
),
);
function getUniqueHotels($hotels) {
$uniqueHotels = array();
foreach($hotels as $hotel) {
$niddle = $hotel['hotelID'];
if(array_key_exists($niddle, $uniqueHotels)) continue;
$uniqueHotels[$niddle] = $hotel;
}
return $uniqueHotels;
}
$unique_hotels = getUniqueHotels($hotels);
print_r($unique_hotels);
results in:
Array
(
[10] => Array
(
[id] => 1
[hotelID] => 10
)
[20] => Array
(
[id] => 3
[hotelID] => 20
)
)

Answer 2

You could simply loop through the array and add them to a new array, indexed by hotelID. This way any duplicates will just overwrite the existing value and you end up with one entry per hotel:
$unique = array();
foreach ($hotels as $value)
{
$unique[$value['hotelID']] = $value;
}
$data['uniqueHotels'] = array_values($unique);

Answer 3

Here is a dynmaic solution:
function uniqueAssocArray($array, $uniqueKey){
$unique = array();
foreach ($array as $value){
$unique[$value[$uniqueKey]] = $value;
}
$data = array_values($unique);
return $data;
}
How to use:
uniqueAssocArray($yourArray, 'theKey');

Answer 4

along the lines of what you're trying,
array_unique(array_map(function($hotel) { return $hotel['hotelID']; }, $array))