Is there a way to combine these two functions? Category System

Combining is easy:

PHP Code:

if( $subject_list = $this->Posts_categories_model->get_list() )
{
    foreach( $subject_list as $sub )
    {
        $data['subject_options'][$sub->id]         = $sub->title;
        $data['subject_name_options'][$sub->title] = $sub->title; 
    }
} 


If I do that I just get them repated, the difference between them is the value would "value=1" or value="category-one".
Not just that I' trying to add them here(the first two lines):

PHP Code:

           $data = array(
                'subject_id'    => $this->input->post('subject_id'),
// Obviously the input below will not work but I had to try it out.
                'subject_name'    => $this->input->post($sub->title),
                'slug'            => $slug,
                'title'            => $this->input->post('title'),
                'post_image'    => $post_image,
                'body'            => $this->input->post('body'),
                'is_published'    => $this->input->post('is_published'),
            ); 


Doing it as you say it would just fill the subject_id input, and I want one input to fill the two values.
How can I fill in the second value(subject_name) according to the subject_id?

I do Front-End development most of the time