Paul Rubin <http://[EMAIL PROTECTED]> wrote:
> [EMAIL PROTECTED] (Alex Martelli) writes:
> > ...which suggests that creating an xrange object is _cheaper_ than
> > indexing a list...
>
> Why not re-use the xrange instead of keeping a list around?
>
> Python 2.4.4 (#1, Oct 23 2006, 13:58:00)
> >>> a = xrange(3)
> >>> print list(a)
> [0, 1, 2]
> >>> print list(a)
> [0, 1, 2]
Reusing xranges is exactly what my code was doing -- at each for loop
you need an xrange(1, k) for a different value of k, which is why you
need some container to keep them around (and a list of xrange objects is
the simplest applicable container).
Your suggestion doesn't appear to make any sense in the context of the
optimization problem at hand -- what list(...) calls are you thinking
of?! Please indicate how your suggestion would apply in the context of:
def f3(M=M, solutions=solutions):
"pull out all the stops"
xrs = [xrange(1, k) for k in xrange(0, M+1)]
for a in xrs[M]:
a2 = a*a
for b in xrs[M-a]:
s = a2 + b*b
for c in xrs[M-a-b]:
if s == c*c:
solutions[a+b+c] += 1
Alex
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