Programatically sort a merged view by a row value

Question

I am using the following hook_views_pre_render to merge 2 views_data_export views.

function hook_views_pre_render(ViewExecutable $view) {
  if ($view->id() == 'commerce_orders' && $view->current_display == 'data_export_1') {
    $first_extra_results_view = Views::getView('commerce_orders');
    $first_extra_results_view->setDisplay('data_export_2');
    $first_extra_results_view->execute();
    $first_extra_results_view->result;
    $view->result = array_merge($view->result, $first_extra_results_view->result);

  }
}

Both of the views are sorted by order_number, but array_merge is just stacking them on one another (as expected).

$view order_1
$view order_2
$first_extra_results_view order_1
$first_extra_results_view order_2

I would like to know how to take the new $view->result and re-apply the sort criteria so that the output of the $view->result would be this:

$view order_1
$first_extra_results_view order_1
$view order_2
$first_extra_results_view order_2

I am able to get the order number for each result, but I don't know how to sort the view results by those order numbers:

foreach ($results as $key => $value) {
  $order_number = $value->commerce_order_order_number;
}

Answer 1

I was able to work this out quite simply. I put the array_merge() into a $results variable:

$results = array_merge($view->result, $first_extra_results_view->result);

To get the $order_number for each of the $results, I used array_column():

$order_number = array_column($results, 'commerce_order_order_number');

Then to sort the $results by $order_number I used array_multisort().:

array_multisort($order_number, SORT_DESC, $results);

I did also have to re-sort the entire array for some reason, but all in all this is what I came up with:

function hook_views_pre_render(ViewExecutable $view) {
  if ($view->id() == 'commerce_orders' && $view->current_display == 'data_export_1') {
    $first_extra_results_view = Views::getView('commerce_orders');
    $first_extra_results_view->setDisplay('data_export_2');
    $first_extra_results_view->execute();
    $first_extra_results_view->result;
    $results = array_merge($view->result, $first_extra_results_view->result);

    // Sort the rows by order number.
    $order_number = array_column($results, 'commerce_order_order_number');
    array_multisort($order_number, SORT_DESC, $results);

    // Sort the rows so that shipping items are back on the bottom.
    krsort($results);
    $view->result = $results;
  }
}