An ordering question

[Kottiyath]

Hi,
    I have 2 lists
a = [(4, 1), (7, 3), (3, 2), (2, 4)]
b = [2, 4, 1, 3]

    Now, I want to order _a_ (a[1]) based on _b_.
    i.e. the second element in tuple should be the same as b.
    i.e. Output would be [(3, 2), (2, 4), (4, 1), (7, 3)]

    I did the same as follows:
>>> l = len(a) * [None]
>>> for (k, v) in a:
...   for i, e in enumerate(b):
...     if e == v:
...        l[i] = (k, v)

     This works, but the code -for python- looks very kludgy.
     I thought for ~2 hours to see whether I can do it in a line or 2,
but I cannot seem to find a mechanism.
     Can someone help me out?