Hi all,
I am trying to clean up, categorify and upload my old code for
wrapping GAP conjugacy classes into Sage.
Following the suggestion from Nicolas Thiery, I have two main classes
ConjugacyClass(Parent) for the generic methods and
ConjugacyClassGAP(ConjugacyClass) for wrapping GAP methods. In
particular, the generic method for computing the set of all the
elements in a conjugacy class gets overridden by the fastest GAP
method when available.
As of now, the GAP wrapper for computing this sets may fail due to
some issues when converting GAP matrix groups into Sage groups, so I
would like the ConjugacyClassGAP.set() method to fall back to
ConjugacyClass.set() method, but this fails when the method in the
base category is cached. Here is a stripped down version of my code (I
only include the __init__ and set methods):
class ConjugacyClass(Parent):
def __init__(self, group, element):
self._parent = group
self._representative = element
Parent.__init__(self)
@cached_method
def set(self):
from sage.sets.set import Set
if self._parent.is_finite():
g = self._representative
G = self._parent
return Set(x*g*x**(-1) for x in G)
else:
raise NotImplementedError, "Listing the elements of
conjugacy \
classes is not implemented for infinite groups!"
class ConjugacyClassGAP(ConjugacyClass):
def __init__(self, group, element):
try:
self._gap_group = group._gap_()
self._gap_representative = element._gap_()
ConjugacyClass.__init__(self,group, element)
except:
raise TypeError, "The group %s cannot be defined as a GAP
group"%group
@cached_method
def set(self):
"""
from sage.sets.set import Set
try:
cc =
self._gap_group.ConjugacyClass(self._gap_representative).AsList().sage()
return Set([self._parent(x) for x in cc])
except NotImplementedError: # If GAP doesn't work, fall
back to naive method
return ConjugacyClass.set(self) # <-- THIS IS THE
TROUBLING CALL!
the problem is with the last line (the fallback method). If I leave it
like this then sage complains about the number of arguments in the set
method:
sage: F = GF(5)
sage: gens = [matrix(F,2,[1,2, -1, 1]), matrix(F,2, [1,1, 0,1])]
sage: H = MatrixGroup(gens)
sage: h = H(matrix(F,2,[1,2, -1, 1]))
sage: C = ConjugacyClassGAP(H,h)
sage: C.set()
ERROR: An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line statement', (396, 0))
ERROR: An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line statement', (396, 0))
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/Users/javier/<ipython console> in <module>()
/Applications/sage/local/lib/python2.6/site-packages/sage/misc/
cachefunc.pyc in __call__(self, *args, **kwds)
553 return self.cache[k]
554 except KeyError:
--> 555 w =
self._cachedmethod._instance_call(self._instance, *args, **kwds)
556 self.cache[k] = w
557 return w
/Applications/sage/local/lib/python2.6/site-packages/sage/misc/
cachefunc.pyc in _instance_call(self, inst, *args, **kwds)
776
777 """
--> 778 return self._cachedfunc.f(inst, *args, **kwds)
779
780 def _get_instance_cache(self, inst):
/Applications/sage/local/lib/python2.6/site-packages/sage/groups/
conjugacy_classes.pyc in set(self)
300 try:
301 cc =
self._gap_group.ConjugacyClass(self._gap_representative).AsList().sage()
302 return Set([self._parent(x) for x in cc])
303 except NotImplementedError: # If GAP doesn't work,
fall back to naive method
--> 304 return ConjugacyClass.set(self)
/Applications/sage/local/lib/python2.6/site-packages/sage/misc/
cachefunc.pyc in __call__(self, *args, **kwds)
553 return self.cache[k]
554 except KeyError:
--> 555 w =
self._cachedmethod._instance_call(self._instance, *args, **kwds)
556 self.cache[k] = w
557 return w
/Applications/sage/local/lib/python2.6/site-packages/sage/misc/
cachefunc.pyc in _instance_call(self, inst, *args, **kwds)
776
777 """
--> 778 return self._cachedfunc.f(inst, *args, **kwds)
779
780 def _get_instance_cache(self, inst):
TypeError: set() takes exactly 1 argument (2 given)
If I remove the @cached_method decorator from the base class
(ConjugacyClass) then the fallback works perfectly:
age: F = GF(5)
sage: gens = [matrix(F,2,[1,2, -1, 1]), matrix(F,2, [1,1, 0,1])]
sage: H = MatrixGroup(gens)
sage: h = H(matrix(F,2,[1,2, -1, 1]))
sage: C = ConjugacyClassGAP(H,h)
sage: C.set()
{[3 2]
[2 4], [0 1]
[2 2], [3 4]
[1 4], [0 3]
[4 2], [1 2]
[4 1], [2 1]
[2 0], [4 1]
[4 3], [4 4]
[1 3], [2 4]
[3 0], [1 4]
[2 1], [3 3]
[3 4], [2 3]
[4 0], [0 2]
[1 2], [1 3]
[1 1], [4 3]
[3 3], [4 2]
[2 3], [0 4]
[3 2], [1 1]
[3 1], [2 2]
[1 0], [3 1]
[4 4]}
All my testing has been done in Sage 4.7.2 in a Mac OS-X 10.6.8
Is this a (known) problem with the cached_method decorator, or am I
doing something wrong?
Cheers,
Javier
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