how to do a numeric sort

[scidam]

Below is not an universal approach, but it might be useful:

def key(x):
    vals = map(int, x.split('.'))
    vv = [1000, 50, 1]
    return sum(x * y for x, y in zip(vv, vals))

sorted(['3.1.3', '3.1.1', '3.1.9', '3.2.1', '3.1.10'], key=key)

Output:
['3.1.1', '3.1.3', '3.1.9', '3.1.10', '3.2.1']