Adding a radio buttons in views exposed filters for published and unpublished drupal 7
This can be achieved using Better Exposed Filters module. If you need to do this programmaticaly then you may need to look at the code of this module. You need to implement the hook_theme as done in better_exposed_filters.module and implement the code to display as radio button as done in better_exposed_filters.theme(Function: theme_select_as_radios)

I would suggest using the module directly if that is an option.