PHP - Merge Two Associative Arrays where values match [duplicate] - php

Question

This question already has answers here:
Array merge on key of two associative arrays in php?
(2 answers)
Closed 9 months ago.
I have two arrays that need to be merged. I can loop through each array and merge manually. But, Is there a built in function to do this?
Array 1:
Array
(
[0] => Array
(
[detail_image_id] => 6389
[product_name] => Starter broadband Package
)
[1] => Array
(
[detail_image_id] => 6358
[product_name] => Starter broadband Package
)
)
Array 2:
Array
(
[0] => Array
(
[detail_image_id] => 6358
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-wingle.jpg
)
[1] => Array
(
[detail_image_id] => 6389
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-charji.jpg
)
)
Expected Output array is:
Array
(
[0] => Array
(
[detail_image_id] => 6389
[product_name] => Starter broadband Package
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-charji.jpg
)
[1] => Array
(
[detail_image_id] => 6358
[product_name] => Starter broadband Package
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-wingle.jpg
)
)
I have added only a sample from the array. Array is huge. Is there any PHP functions like array_merge() or array_map() that we can use instead of manual for loops and iterators?

Answer 1

Older & wiser: I've scrubbed my answer from years earlier because I no longer recommend the techniques. It will be most succinct and efficient to merge the arrays, feed them to a foreach() loop, then "unite" (+ is used as an array union operator) data in related rows.
The null coalescing operator (??) is used to ensure that there is always something to "unite" with.
Code: (Demo)
$result = [];
foreach (array_merge($array1, $array2) as $row) {
$result[$row['detail_image_id']] = ($result[$row['detail_image_id']] ?? []) + $row;
}
var_export(array_values($result));
Output:
array (
0 =>
array (
'detail_image_id' => '6389',
'product_name' => 'Starter broadband Package',
'guid' => 'http://xxx/wp-content/uploads/2018/04/broadband-4mbs-charji.jpg',
),
1 =>
array (
'detail_image_id' => '6358',
'product_name' => 'Starter broadband Package',
'guid' => 'http://xxx/wp-content/uploads/2018/04/broadband-4mbs-wingle.jpg',
),
)

Answer 2

You can do something like:
$arr1 = array(); //Your array 1
$arr2 = array(); //Your array 2
//Make a temp array to that use detail_image_id as the key
$arr1Temp = array_combine( array_column($arr1,'detail_image_id'), $arr1 );
$arr2Temp = array_combine( array_column($arr2,'detail_image_id'), $arr2 );
//Get All unique detail_image_id from 2 arrays.
//This is to make sure that all detail_image_id's will be included.
//detail_image_id on 2nd array might not be present on the 1st one
$imgIds = array_unique(array_merge( array_keys($arr1Temp), array_keys($arr2Temp) ));
//Do a simple foreach loop
$result = array();
foreach( $imgIds as $val ) {
$result[] = array_merge( $arr1Temp[$val], $arr2Temp[$val] );
}
print_r( $result );
This will result to:
Array
(
[0] => Array
(
[detail_image_id] => 6389
[product_name] => Starter broadband Package
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-charji.jpg
)
[1] => Array
(
[detail_image_id] => 6358
[product_name] => Starter broadband Package
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-wingle.jpg
)
)

Answer 3

You can use a combination of array_column() and array_combine() to create a reference array using the detail_image_id as key. Then, with a foreach() loop, you can merge arrays using + operator:
$array1 = [
['detail_image_id' => '6389', 'product_name' => 'Starter broadband Package'],
['detail_image_id' => '6358', 'product_name' => 'Starter broadband Package']
];
$array2 = [
['detail_image_id' => '6358', 'guid' => 'http://xxx/wp-content/uploads/2018/04/broadband-4mbs-wingle.jpg'],
['detail_image_id' => '6389', 'guid' => 'http://xxx/wp-content/uploads/2018/04/broadband-4mbs-charji.jpg']
];
// create associative array with detail_image_id as key,
$out = array_combine(array_column($array1, 'detail_image_id'), $array1);
foreach ($array2 as $item) {
$key = $item['detail_image_id']; // shortcut for the key,
$out[$key] = $out[$key] + $item; // merge arrays
}
print_r(array_values($out)); // reset to indexed keys (0,1,2...)
Output:
Array
(
[0] => Array
(
[detail_image_id] => 6389
[product_name] => Starter broadband Package
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-charji.jpg
)
[1] => Array
(
[detail_image_id] => 6358
[product_name] => Starter broadband Package
[guid] => http://xxx/wp-content/uploads/2018/04/broadband-4mbs-wingle.jpg
)
)