Custom datatables sort function where cell has two values

I am using datatables and in one column the cells "td" elements have the following html within. <td> <h4 data-pos="5">5</h4> <span data-second="-4">-4</span> </td> I have a custom drop down in the table header with two buttons. Each button's click event is linked to this column and the associate data attributes. On click I would like the column to be sorted by either data-pos or data-second depending on the button clicked. So you will need to write a function to get the data attributes and either re order the table or sort the table by these values.