On 3/26/2011 12:17 AM, Stefan Behnel wrote:
Not restarted in the sense that it gets cleaned up, though. The above
simply passes an explicit value for it that will be used for the single
call.
Which satisfies the time test need, but...
Future calls won't be affected.
Good point. If one does
On Mar 26, 5:10 pm, Terry Reedy tjre...@udel.edu wrote:
On 3/26/2011 12:17 AM, Stefan Behnel wrote:
Not restarted in the sense that it gets cleaned up, though. The above
simply passes an explicit value for it that will be used for the single
call.
Which satisfies the time test need,
Stefan Behnel stefan...@behnel.de writes:
Not restarted in the sense that it gets cleaned up, though. The
above simply passes an explicit value for it that will be used for the
single call. Future calls won't be affected.
Stefan
About this global caching thing I thought, but isn't this a
On Sat, 26 Mar 2011 12:06:46 +0100, Andrea Crotti wrote:
About this global caching thing I thought, but isn't this a source of
possible HUGE memory leaks?
Hypothetically, but probably not that huge. And I wouldn't call it a
*leak* as such, since you can access the memory and recover it if you
On Saturday, March 26, 2011 7:50:36 AM UTC-4, Steven D#39;Aprano wrote:
That's of the order of 200 MB of memory -- not that much for today's
systems. I've had people email me .doc files that big *wink*
Yikes! I know this thread is about caching the output of a function, but in the
example
On Sat, 26 Mar 2011 07:14:17 -0700, eryksun () wrote:
On Saturday, March 26, 2011 7:50:36 AM UTC-4, Steven D#39;Aprano wrote:
That's of the order of 200 MB of memory -- not that much for today's
systems. I've had people email me .doc files that big *wink*
Yikes! I know this thread is
On 3/26/2011 5:55 AM, Lie wrote:
On Mar 26, 5:10 pm, Terry Reedytjre...@udel.edu wrote:
On 3/26/2011 12:17 AM, Stefan Behnel wrote:
Not restarted in the sense that it gets cleaned up, though. The above
simply passes an explicit value for it that will be used for the single
call.
Which
On Saturday, March 26, 2011 11:49:02 AM UTC-4, Steven D#39;Aprano wrote:
def fib(n):
phi = (5 ** 0.5 + 1) / 2
f = (phi ** n - (1 - phi) ** n) / 5 ** 0.5
return int(f)
Have you tried it?
Unfortunately, with floating point rounding error, that rapidly
On 3/26/2011 7:06 AM, Andrea Crotti wrote:
Stefan Behnelstefan...@behnel.de writes:
Not restarted in the sense that it gets cleaned up, though. The
above simply passes an explicit value for it that will be used for the
single call. Future calls won't be affected.
Stefan
About this global
On 3/26/2011 11:49 AM, Steven D'Aprano wrote:
On Sat, 26 Mar 2011 07:14:17 -0700, eryksun () wrote:
Yikes! I know this thread is about caching the output of a function, but
in the example of Fibonacci numbers, we're blessed with an easily
derived closed form expression (via Z transform, etc):
On Sat, 26 Mar 2011 10:25:31 -0700, eryksun () wrote about Fibonacci
function:
That's true. If you need more than double precision, obviously it's time
to defer to the experts. Here's an O(n) algorithm:
http://www.gnu.org/software/gmp/manual/html_node/Fibonacci-Numbers-
Algorithm.html
We
Terry Reedy tjre...@udel.edu writes:
For the reason Stefan explained and hinted above. Try the following instead:
def fib_iter(n, _cache = [1,1]):
k = len(_cache)
if n = k:
for i in range(k, n+1):
_cache.append(_cache[i-2] + _cache[i-1])
return _cache[n]
This should be
Andrea Crotti, 25.03.2011 09:49:
Terry Reedy writes:
For the reason Stefan explained and hinted above. Try the following instead:
def fib_iter(n, _cache = [1,1]):
k = len(_cache)
if n= k:
for i in range(k, n+1):
_cache.append(_cache[i-2] + _cache[i-1])
return _cache[n]
On Fri, 2011-03-25 at 09:49 +0100, Andrea Crotti wrote:
Terry Reedy tjre...@udel.edu writes:
For the reason Stefan explained and hinted above. Try the following instead:
def fib_iter(n, _cache = [1,1]):
k = len(_cache)
if n = k:
for i in range(k, n+1):
On Thursday, March 24, 2011 8:12:22 PM UTC-4, Terry Reedy wrote:
If Python did what some have asked, which is to make 'recursive'
functions actually recursive by replacing a local variable that matches
the function name (in this 'fib') with a direct reference to the
function itself, as a
eryksun () eryk...@gmail.com writes:
Regarding this I have question about function attributes. Is there an
equivalent of 'self' for functions? I've seen people use function
attributes as local static variables, but this seems problematic when
all you have is a global reference to the
On Friday, March 25, 2011 6:53:48 AM UTC-4, Andrea Crotti wrote:
I had never seen such a thing, but why would this make sense at all?
When does it make sense logically for a function to have an attribute?
A function should have some input, some local variables to compute
temporary results
eryksun () eryk...@gmail.com writes:
See Pep 232: http://www.python.org/dev/peps/pep-0232
Also, see the discussion thread on Python-Dev:
http://mail.python.org/pipermail/python-dev/2000-April/thread.html#3282
I don't think self-referenced static variables (as in C's static
declaration) are
On 3/25/2011 4:49 AM, Andrea Crotti wrote:
Terry Reedytjre...@udel.edu writes:
def fib_iter(n, _cache = [1,1]):
k = len(_cache)
if n= k:
for i in range(k, n+1):
_cache.append(_cache[i-2] + _cache[i-1])
return _cache[n]
I just realized that the signature really ought to
On 3/25/2011 5:16 AM, Stefan Behnel wrote:
Terry's version is playing with the fact that default arguments are only
instantiated once, i.e. (unless overridden by passing an explicit
argument) the _cache is shared over all calls to the function. This is
similar to what your memoization decorator
Terry Reedy, 25.03.2011 21:18:
On 3/25/2011 5:16 AM, Stefan Behnel wrote:
Terry's version is playing with the fact that default arguments are only
instantiated once, i.e. (unless overridden by passing an explicit
argument) the _cache is shared over all calls to the function. This is
similar to
I was showing a nice memoize decorator to a friend using the classic
fibonacci problem.
--8---cut here---start-8---
def memoize(f, cache={}):
def g(*args, **kwargs):
# first must create a key to store the arguments called
# it's
Andrea Crotti, 24.03.2011 14:48:
I was showing a nice memoize decorator to a friend using the classic
fibonacci problem.
--8---cut here---start-8---
def memoize(f, cache={}):
def g(*args, **kwargs):
# first must create a key to store the
On 3/24/2011 9:48 AM, Andrea Crotti wrote:
def fib_iter(n):
ls = {0: 1, 1:1}
Storing a linear array in a dict is a bit bizarre
for i in range(2, n+1):
ls[i] = ls[i-1] + ls[i-2]
return ls[max(ls)]
So is using max(keys) to find the highest index, which
On 3/24/2011 9:48 AM, Andrea Crotti wrote:
I was showing a nice memoize decorator to a friend using the classic
fibonacci problem.
--8---cut here---start-8---
def memoize(f, cache={}):
def g(*args, **kwargs):
# first must create a key to
On Thu, Mar 24, 2011 at 08:12:22PM -0400, Terry Reedy wrote:
The irony of this is that memoizing 'recursive' functions with a
decorator depends on the fact the Python does not have truly recursive
functions. A function cannot call itself directly.
I wonder what exactly is meant by that
On 3/24/2011 8:26 PM, Fons Adriaensen wrote:
On Thu, Mar 24, 2011 at 08:12:22PM -0400, Terry Reedy wrote:
The irony of this is that memoizing 'recursive' functions with a
decorator depends on the fact the Python does not have truly recursive
functions. A function cannot call itself directly.
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