Php twig转换

Does anyone know how to convert this php to twig?

<?php echo isset(${'discount_value' . $customer_group['customer_group_id']}) ? ${'discount_value' . $customer_group['customer_group_id']} : ''; ?>

Because when i convert it into this:

{{ 'discount_value' ~ customer_group.customer_group_id ? 'discount_value' ~ customer_group.customer_group_id : '' }}

it will return as a string, instead of variable.

In php it will return eg: $discount_value1

Try using _context for this:

{% set discount_value = _context['discount_value' ~ customer_group.customer_group_id] is defined ? _context['discount_value' ~ customer_group.customer_group_id] : '' %}

and then echo discount_value