Repton wrote: > I often find myself storing data in a list of tuples, and I want to ask > questions like "what is the index of the first tuple whose 3rd element > is x", or "give me the first tuple whose 2nd element is y". > > I know I can do [elem for elem in lst if elem[3] == x][0] or (elem for > elem in lst if elem[2] == y).next() but it feels kinda ugly; is there a > better way? > > (something like lst.index(x, key=..) or lst.find(y, key=..) would be > nice)
>>> items = [(1, "a", 10), (2, "b", 20), (3, "c", 30)] >>> class Key(object): ... def __init__(self, key): ... self.key = key ... def __eq__(self, other): ... return self.key(other) ... >>> items.index(Key(lambda x: x[2] == 20)) 1 >>> items.index(Key(lambda x: x[1] == "c")) 2 A cleaner and probably faster solution would be to subclass list and override index()/find(). Peter -- http://mail.python.org/mailman/listinfo/python-list
