Merge 2 Multi-dimensional arrays with some duplicate values - php

Question

I have two arrays that sometimes have matching keys, and I need to merge these values based on the matching fields (make/model/year) and set accordingly based on a value flag each array object has (in this case either fit: B or fit: R)
The first array looks like this and contains fit B's:
$firstArray = [
{ Model: Aston Martin, Make: V12, Year: 2012, fit: B, front_fit: 52, rear_fit: null}
]
Here is the second array and it contains only fit R's:
$secondArray = [
{ Model: Aston Martin, Make: V12, Year: 2012, fit: R, front_fit: null, rear_fit: 24}
]
Notice how most of the values are the same except fit and the front or rear fit based on that flag (B or R). Ideally I would like to merge these two in a new array that would remove the fit and fill out the front_fit and rear_fit fields accordingly:
$mergedNewArray = [
{ Model: Aston Martin, Make: V12, Year: 2012, front_fit: 52, rear_fit: 24}
]
There is a potential third scenario to happen where there may not be a matching model/make/year object in one of the arrays, if this is the case I still want to include the existing record in the new array
so it would turn into something like this:
$mergedNewArray = [
{ Model: Aston Martin, Make: V12, Year: 2012, front_fit: 52, rear_fit: 24},
//This has no matching object to merge with but should still be in this array
{ Model: Dodge, Make: Charger, Year: 2006, front_fit: null, rear_fit: 80}
]
Any help would be much appreciated, The less verbose the better
Edit: Added clarification for the first array and second array containing specific fits

Answer 1

Probably the easiest way to do this is to re-index the first array by the make/model/year, and then iterate over the second array, looking for the same car and if found, updating the record, otherwise creating a new entry in the output. The result array can then be re-indexed numerically using array_values:
$firstArray = json_decode('[
{ "Model": "Aston Martin", "Make": "V12", "Year": 2012, "fit": "B", "front_fit": 52, "rear_fit": null },
{ "Model": "Aston Martin", "Make": "Vantage", "Year": 2017, "fit": "B", "front_fit": 40, "rear_fit": null }
]', true);
$secondArray =json_decode('[
{ "Model": "Aston Martin", "Make": "V12", "Year": 2012, "fit": "R", "front_fit": null, "rear_fit": 24 },
{ "Model": "Dodge", "Make": "Charger", "Year": 2006, "fit": "R", "front_fit": null, "rear_fit": 80 }
]', true);
$result = array();
// index the first array by the model, make and year
foreach ($firstArray as $car) {
unset($car['fit']);
$key = $car['Model'] . '#' . $car['Make'] . '#' . $car['Year'];
$result[$key] = $car;
}
foreach ($secondArray as $car) {
$key = $car['Model'] . '#' . $car['Make'] . '#' . $car['Year'];
// have we seen this car?
if (isset($result[$key])) {
// if so, update
$result[$key]['rear_fit'] = $car['rear_fit'];
}
else {
// create a new entry
unset($car['fit']);
$result[$key] = $car;
}
}
// reindex to numeric keys
$result = array_values($result);
print_r($result);
Output:
Array
(
[0] => Array
(
[Model] => Aston Martin
[Make] => V12
[Year] => 2012
[front_fit] => 52
[rear_fit] => 24
)
[1] => Array
(
[Model] => Aston Martin
[Make] => Vantage
[Year] => 2017
[front_fit] => 40
[rear_fit] =>
)
[2] => Array
(
[Model] => Dodge
[Make] => Charger
[Year] => 2006
[front_fit] =>
[rear_fit] => 80
)
)
Demo on 3v4l.org