Conditionally adding items to an array with if statements

I've got the code working after a lot of fiddling and googling, but I have a strong suspicion that there is a much better way to accomplish what I'm doing. Is this a place where I can ask for help to clean up and improve my code? If so, thanks in advance!

This code is modifying a wordpress loop.

The goal: Check the roles of the current user and show posts of certain categories, based on the user roles.

My working code:

/** Check if the current user is a Student, and if they are, run the custom loop. */
$current_user = wp_get_current_user();
$roles = $current_user->roles;
if ($roles[0] == 'student'){

   /** Replace the standard loop with our custom loop */
   remove_action( 'genesis_loop', 'genesis_do_loop' );
   add_action( 'genesis_loop', 'custom_student_loop' );
 
   function custom_student_loop() {

      $grades = array(); //Set up an empty array for the grades. We're gonna add grade categories as necessary based on user roles.

      /** Check the roles of the current user, and add grade categories to the Grades array as needed */
      $user = wp_get_current_user();
      if ( in_array( 'grade_1_student', (array) $user->roles ) ) {
         $grades[] = ('grade-1');
      }
      if ( in_array( 'grade_2_student', (array) $user->roles ) ) {
         $grades[] = ('grade-2');
      }
      if ( in_array( 'grade_3_student', (array) $user->roles ) ) {
         $grades[] = ('grade-3');
      }
      if ( in_array( 'grade_4_student', (array) $user->roles ) ) {
         $grades[] = ('grade-4');
      }
      if ( in_array( 'grade_5_student', (array) $user->roles ) ) {
         $grades[] = ('grade-5');
      }
      if ( in_array( 'grade_6_student', (array) $user->roles ) ) {
         $grades[] = ('grade-6');
      }
      if ( in_array( 'grade_7_student', (array) $user->roles ) ) {
         $grades[] = ('grade-7');
      }
      if ( in_array( 'grade_8_student', (array) $user->roles ) ) {
         $grades[] = ('grade-8');
      }
      if ( in_array( 'grade_9_student', (array) $user->roles ) ) {
         $grades[] = ('grade-9');
      }

       global $paged; // current paginated page
       global $query_args; // grab the current wp_query() args
            $args = array(
                'paged'            => $paged, // respect pagination
                'tax_query' => array(
                 array(
                     'taxonomy' => 'homework-grades',
                     'field'    => 'slug',
                     'terms'    => $grades,
                 ),
              ),
            );
         
       genesis_custom_loop( wp_parse_args($query_args, $args) );  
   }

}

Like I said, I'm sure there's a cleaner/better way to do this but I have not been able to find any examples to follow, and I've searched everything I can think of that would apply to this, but I don't know where else to look. If anyone can give me suggestions or point me in the right direction, that would be very much appreciated.

Thanks!

source https://stackoverflow.com/questions/71211054/conditionally-adding-items-to-an-array-with-if-statements