Kyle,
I didn't apply the patch you have below. For SAGE-2.5, I did,
however, make some changes to how sets and hashing of sets works so
that your examples work fine, and I included them in the docstrings.
Basically, now finite sets will have their frozenset computed when the
set is created.
-- William
On 4/13/07, Kyle Schalm <[EMAIL PROTECTED]> wrote:
>
>
> i discovered a bug when i tried to use a Set as a dictionary key. i've
> included a patch below. i have also created a test case illustrating the
> bug -- in the future, where do i put this in the code/docs so it can go in
> the patch too?
>
> here is the test case:
>
> ---
> In [72]: d={Set([2*I,1+I]):1}
>
> In [73]: d[Set([1+I,2*I])]
> <type 'exceptions.KeyError'>
> ---
>
> note that this bug only occurs when python doesn't know
> how to sort the elements in the Set. e.g.:
>
> In [74]: d={Set([1,2]):1}
>
> In [75]: d[Set([2,1])]
> Out[75]: 1
>
> works because Set([1,2]) and Set([2,1]) print the same:
>
> In [76]: Set([1,2])
> Out[76]: {1, 2}
>
> In [77]: Set([2,1])
> Out[77]: {1, 2}
>
> while
>
> In [78]: Set([2*I,1+I])
> Out[78]: {2.00000000000000*I, 1.00000000000000 + 1.00000000000000*I}
>
> In [79]: Set([1+I,2*I])
> Out[79]: {1.00000000000000 + 1.00000000000000*I, 2.00000000000000*I}
>
> print differently.
> this in turn led to a different hash value, since the default hash value
> comes from the string representation.
> ---
>
> below is the patch.
>
>
>
> # HG changeset patch
> # User Kyle Schalm <[EMAIL PROTECTED]>>
> # Date 1176451637 18000
> # Node ID bca0cc86fd5e88dc21887c5d222c1fcfa71ae490
> # Parent 76e21a785e866569cc43a15b01ee81d9dd131b43
> fix bug when using Set as dictionary key
>
> diff -r 76e21a785e86 -r bca0cc86fd5e sage/sets/set.py
> --- a/sage/sets/set.py Fri Apr 13 00:29:21 2007 -0500
> +++ b/sage/sets/set.py Fri Apr 13 03:07:17 2007 -0500
> @@ -505,7 +505,7 @@ class Set_object_enumerated(Set_object):
>
> def _repr_(self):
> s = str(self.set())
> - return "{" + s[5:-2] + "}"
> + return "{" + s[11:-2] + "}"
> # return "Finite set of elements of %s"%self.__object
>
> def set(self):
> @@ -530,8 +530,11 @@ class Set_object_enumerated(Set_object):
> try:
> return self.__set
> except AttributeError:
> - self.__set = set(self.object())
> + self.__set = frozenset(self.object())
> return self.__set
> +
> + def __hash__(self):
> + return hash(self.set())
>
> def __cmp__(self, other):
> """
>
>
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://www.williamstein.org
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