[sage-combinat-devel] Re: [sage-devel] sage.combinat.combinat.combinations and sage.combinat.combination.Combinations
Dear Tim,
On Tue, Jan 12, 2010 at 10:58:23PM +0800, Tim Joseph Dumol wrote:
I've been wondering why sage.combinat.combinat.combinations still exists,
when sage.combinat.combination.Combinations is much faster, being native
Sage code, and thus not requiring GAP interfacing (also more reliable, I
suppose). The huge speed differnce can be seen here:
{{{
sage: timeit('[Combinations(range(i), j).list() for (i, j) in
CartesianProduct(range(15), range(15))]')
5 loops, best of 3: 449 ms per loop
sage: timeit('[combinations(range(i), j) for (i, j) in
CartesianProduct(range(15), range(15))]')
5 loops, best of 3: 4.17 s per loop
}}}
`combinations` is 10x slower than `Combinations`. If compatibility needs
to be maintained, `combinations(mset,k)` can be defiend as an alias to
`Combinations(mset,k).list`.
Thanks for the report!
Could you please open a track ticket and send us a patch, with an
alias as you suggest, and possibly a deprecation warning? Note: the
following (dubious) feature advertised in 'combinations?' might be
vaguely tricky to emulate:
sage: mset = [d,a,v,i,d]
sage: combinations(mset,3)
['add', 'adi', 'adv', 'aiv', 'ddi', 'ddv', 'div']
Thanks in advance!
Best,
Nicolas
--
Nicolas M. Thiéry Isil nthi...@users.sf.net
http://Nicolas.Thiery.name/
--
You received this message because you are subscribed to the Google Groups
sage-combinat-devel group.
To post to this group, send email to sage-combinat-de...@googlegroups.com.
To unsubscribe from this group, send email to
sage-combinat-devel+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sage-combinat-devel?hl=en.
Re: [sage-combinat-devel] Re: Category Questions
Hi Jason! On Tue, Jan 12, 2010 at 12:19:36PM -0500, Jason Bandlow wrote: While working on this, I added a ``TestSuite(phi)`` test where ``phi`` is a TriangularModuleMorphism, mimicking what was done for DiagonalModuleMorphism. Good idea! Unfortunately, pickling fails. I don't really know where to start tracking this down... can you give me a pointer? phi is constructed from f, which itself can't be pickled: sage: X = CombinatorialFreeModule(QQ, [1, 2, 3]); X.rename(X) sage: Y = CombinatorialFreeModule(QQ, [1, 2, 3]); y = Y.basis() sage: f = lambda i: sum( y[j] for j in range(i,4) ) sage: loads(dumps(f)) Traceback (most recent call last): PicklingError: Can't pickle type 'function': attribute lookup __builtin__.function failed That's because functions are pickled by name; but the name of f is __main__.f. Pickles detects that there is no such function in the __main__module, and rightfully deduces that f could not be unpickled in a latter Sage session. Luckily, one can cheat-around this, faking f being picklable, by forcefully inserting it into __main__, as in: sage: import __main__; __main__.f = f Oh, and f should be defined with def, not lambda. sage: X = CombinatorialFreeModule(QQ, [1, 2, 3]); X.rename(X) sage: Y = CombinatorialFreeModule(QQ, [1, 2, 3]); y = Y.basis() sage: def f(i): sum( y[j] for j in range(i,4) ) sage: import __main__; __main__.f = f sage: loads(dumps(f)) function f at 0xbfbc9cc sage: phi = X.module_morphism(f, triangular=True, codomain = Y) sage: TestSuite(phi).run() See the first example of TriangularModuleMorphism. Altogether, whenever possible, I try to use standard sage functions (like factorial) for such building blocks in tests. Here is a handy trick, which involves a bit of magic in sum_of_terms (it's a morphism, and therefore * is function composition): sage: f = Y.sum_of_terms * range sage: f(5) B[0] + B[1] + B[2] + B[3] + B[4] sage: loads(dumps(f)) A map to X Cheers, Nicolas -- Nicolas M. Thiéry Isil nthi...@users.sf.net http://Nicolas.Thiery.name/ -- You received this message because you are subscribed to the Google Groups sage-combinat-devel group. To post to this group, send email to sage-combinat-de...@googlegroups.com. To unsubscribe from this group, send email to sage-combinat-devel+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sage-combinat-devel?hl=en.
Re: [sage-combinat-devel] Re: [sage-devel] sage.combinat.combinat.combinations and sage.combinat.combination.Combinations
Dear Tim, dear sage-combinat,
The huge speed differnce can be seen here:
{{{
sage: timeit('[Combinations(range(i), j).list() for (i, j) in
CartesianProduct(range(15), range(15))]')
5 loops, best of 3: 449 ms per loop
sage: timeit('[combinations(range(i), j) for (i, j) in
CartesianProduct(range(15), range(15))]')
5 loops, best of 3: 4.17 s per loop
}}}
I've got the same
{{{
sage: timeit('[Combinations(range(i),j).list() for (i,j) in
CartesianProduct(range(15),range(15))]')
5 loops, best of 3: 539 ms per loop
sage: timeit('[combinations(range(i),j) for (i,j) in
CartesianProduct(range(15),range(15))]')
5 loops, best of 3: 3.32 s per loop
}}}
But it seems that combinations wrapped from GAP is quicker on
special cases (especially when mset contains repetitions)
{{{
sage: l = [1,1,2,3,4,4,5,6,7,8,8,8,8]
sage: timeit('combinations(l,5)')
25 loops, best of 3: 10.3 ms per loop
sage: timeit('Combinations(l,5).list()')
5 loops, best of 3: 83.7 ms per loop
}}}
Even in mean
{{{
sage: l = [1,1,2,3,4,4,5,6,7,8,8,8,8]
sage: timeit('[combinations(l,i) for i in range(13)]')
5 loops, best of 3: 106 ms per loop
sage: timeit('[Combinations(l,i).list() for i in range(13)]')
5 loops, best of 3: 475 ms per loop
}}}
Vincent
--
You received this message because you are subscribed to the Google Groups
sage-combinat-devel group.
To post to this group, send email to sage-combinat-de...@googlegroups.com.
To unsubscribe from this group, send email to
sage-combinat-devel+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sage-combinat-devel?hl=en.
[sage-combinat-devel] Re: Partitions bug with max_slope?
On Jan 9, 3:58 am, Nicolas M. Thiery nicolas.thi...@u-psud.fr
wrote:
On Sat, Jan 09, 2010 at 10:53:30AM +0100, Vincent Delecroix wrote:
I get the following with sage-4.3, is it normal to have [2, 1] and [1,
2] as partitions ?
{{{
sage: for p in Partitions(3, max_slope=1):
: print p
:
[3]
[2, 1]
[1, 2]
[1, 1, 1]
}}}
Well, that's consistent with max_slope=1. Did you mean max_slope=-1?
Of course, it would have been nicer to get an error (since the highest
meaningful max_slope for a partition is 0). Hopefully we will be able
to do that when the IntegerListsLex kernel will be rewritten
(volunteers for that welcome!).
While we're on this topic, here's a bug which I don't know if anyone
has worked on recently: compare
sage: Partitions(4, max_slope=-1).list()
[[4], [3, 1]]
to
sage: Partitions(4, max_slope=-1, length=3).list() # doesn't work
[[2, 1, 1]]
See http://trac.sagemath.org/sage_trac/ticket/6538.
--
John
--
You received this message because you are subscribed to the Google Groups
sage-combinat-devel group.
To post to this group, send email to sage-combinat-de...@googlegroups.com.
To unsubscribe from this group, send email to
sage-combinat-devel+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sage-combinat-devel?hl=en.
