I currently apply basic asc/desc sort to a column in Python like this:

sort_exprs = [(col.asc() if direction == "asc" else col.desc())]
sorted_dataframe = dataframe.orderBy(*sort_exprs)

One of my columns has data in the format

+-----------------+
|       columnName|
+-----------------+
|           10 (5)|
|             null|
|          15 (20)|
+-----------------+

I’d like to:

1. regardless of what type of sort I use, if a column is being sorted, always move the rows with a null value for that column to the end
2. have the option of sorting by the number in the parentheses. In the example above, I’d sort 5 and 20 instead of 10 and 15. The regex to get the number in the parentheses is r"((d+(.d+)?))"

How would I do this? Thank you in advance