map-like function on dict values?

[Skip Montanaro]

    Huaiyu> Is there a way to do this
    Huaiyu> for k, v in dict.items():
    Huaiyu>     dict[k] = f(v)

    Huaiyu> without involving a Python for loop?

Check out the operator module.  In particular, operator.setitem will
probably do what you want:

    import operator
    keys = dict.keys()
    vals = map(f, dict.values())
    map(operator.setitem, [dict]*len(keys), keys, vals)

    Huaiyu> I'd imagine that a function implemented in C could speed things
    Huaiyu> up quite a bit.  

It all depends on how expensive f() is related to the overhead of a for loop
and the cost of getting map ramped up.  Don't rely on your instincts.
Benchmark it.

-- 
Skip Montanaro (skip at pobox.com - http://www.mojam.com/)