1 str_ranges = "1, 3-7, 12, 15, 18-21"

     2 

     3 ranges = str_ranges.split(',')

     4 

     5 lst = []

     6 for r in ranges:

     7     vals = r.split('-')

     8     if len(vals) == 2:

     9        lst.extend(range(int(vals[0]), int(vals[1]) + 1))

    10     else:

    11        lst.append(int(vals[0]))

    12 

    13 print lst