On 03/07/2008, Emil <[EMAIL PROTECTED]> wrote: > I have created a class called Fibs which allow you to access a specific > number in the > Fibonacci series(http://en.wikipedia.org/wiki/Fibonacci_number) But it seems > to me that it > is a bit inefficient, any suggestions on how to make it more efficient?
Does this behaviour seem correct to you? -- >>> class Fibs(object): ... def __init__(self): ... self.fibsseq = [0, 1] ... def __getitem__(self, key): ... for i in xrange(key): ... self.fibsseq.append(self.fibsseq[-1] + self.fibsseq[-2]) ... return self.fibsseq[key] ... >>> f = Fibs() >>> f[1] 1 >>> f[1] 1 >>> f[1] 1 >>> f.fibsseq [0, 1, 1, 2, 3] Maybe if I examine the first Fibonacci number a few hundred times: >>> ones = [f[1] for i in xrange(500)] >>> len(f.fibsseq) 505 Hmm, that's a lot of numbers to calculate when we're only looking at the first element in the sequence.. (by the way: you might want to replace 'print' with 'return' in your definition of __getitem__) (by the way 2: if you follow the above code, and then display f.fibsseq, you may see some nice curves caused by the " " between each number. Aren't fibonacci numbers wonderful :-) ) -- John. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
