[Tutor] fibonacci

[Don Arnold]

----- Original Message ----- 
From: "Gregor Lingl" <glingl@aon.at>
To: "Bob Gailer" <ramrom@earthling.net>
Cc: <tutor@python.org>
Sent: Friday, February 14, 2003 11:13 AM
Subject: Re: [Tutor] fibonacci


> Bob Gailer schrieb:
> 
> > At 01:24 PM 2/14/2003 +0100, Gregor Lingl wrote:
> >
> >> def fib1liner(n, f=[0,1]):
> >>    return(n+1>len(f))and[(lambda x:f.append(f[-2]+f[-1]))(i)for i in 
> >> range(n+1-len(f))]and 0 or f[n]
> >
> >
> > Thanks for a really great example of what can be done using and, or, 
> > comprehension. FWIW this can be simplified to:
> >
> > def fib1liner(n, f=[0,1]):
> >    return n>1 and[(lambda:f.append(f[-2]+f[-1]))()for i in 
> > range(n-1)]and 0 or f[n]
> >
> Thanks for you compression - concerning the lambda expression.
> However, your oneliner is not exactly eqivalent to the original:
> with every call for n > 1 it computes n-1 new fibonacci numbers, while 
> the original
> version uses the fact, that f - as a mutable object - after every call 
> remains changed.
> so after you have computed fib1liner(20), f contains all 
> fibonacci-numbers up to the 20th.
> Every following call with n<20 needs not to compute anything new.
> Advantages: (1) no unnecessary computing time
>                     (2) no unnecessary memory used
> 
> Gregor
> 
> P.S. What does FWIW mean?
>

The one-liner may be waaay over my head, but FWIW == For What It's Worth.
 
Don