Additional callback 'average_value' for the Calculated Callback addon. Returns the average value of all specified post meta fields (default and additional fields)

average_value_for_calculated.php

<?php 

add_filter( 'jet-engine-calculated-callback/config', function( $callbacks = array() ) {

    $callbacks['average_value'] = function( $field_value, $additional ) {

	if ( empty( $additional ) ) {
		return 'Please set additional meta fields names to calculate';
	}

	$result = is_numeric( $field_value) ? $field_value : 0;
		
	$additional = explode( ',', str_replace( ' ', '', $additional ) );

	foreach ( $additional as $additional_field ) {
			
		$additional_field_value = jet_engine()->listings->data->get_meta( $additional_field );
			
		if ( ! is_numeric( $additional_field_value ) ) {
			return 'The value should be numeric';
		} else {
			$result += $additional_field_value;
		}
			
	}
		
	$divider = count( $additional ) + 1;
		
	$result /= $divider;

        return $result;

    };

    return $callbacks;

} );