Re: [sage-combinat-devel] Re: Constructing homs
On Thu, Dec 06, 2012 at 01:13:09AM +, Dima Pasechnik wrote: > > Here's a related question: suppose I have an object G in sage. Is there a > > "correct" way to ask G if is it a CombinatorialFreeModule? I can check for > > > > if hasattr(G,'_basis_keys'): ... > > > > but I would have thought that there was a better way to do this... > isinstance? > > > sage: F = CombinatorialFreeModule(QQ, ['a','b','c']) > sage: isinstance(F,CombinatorialFreeModule) > True > sage: isinstance([],CombinatorialFreeModule) > False Depending on what you want to test exactly, you might or not want to do sage: F in ModulesWithBasis which will eventually include QQ^3, QQ['x'], ... Cheers, Nicolas -- Nicolas M. Thiéry "Isil" 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-devel@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: Constructing homs
Yes, I worked it out and deleted my question bot before you replied it seems. Thanks anyway, Andrew -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/wWxrvtdzHRoJ. To post to this group, send email to sage-combinat-devel@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: Constructing homs
On 2012-12-05, Andrew Mathas wrote: > --=_Part_33_6944284.1354751535501 > Content-Type: text/plain; charset=ISO-8859-1 > > Here's a related question: suppose I have an object G in sage. Is there a > "correct" way to ask G if is it a CombinatorialFreeModule? I can check for > > if hasattr(G,'_basis_keys'): ... > > but I would have thought that there was a better way to do this... isinstance? sage: F = CombinatorialFreeModule(QQ, ['a','b','c']) sage: isinstance(F,CombinatorialFreeModule) True sage: isinstance([],CombinatorialFreeModule) False HTH, Dima > > Andrew > -- 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-devel@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: Constructing homs
Here's a related question: suppose I have an object G in sage. Is there a "correct" way to ask G if is it a CombinatorialFreeModule? I can check for if hasattr(G,'_basis_keys'): ... but I would have thought that there was a better way to do this... Andrew -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/8axqoe8vKCQJ. To post to this group, send email to sage-combinat-devel@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: Constructing homs
On Wed, Dec 05, 2012 at 10:45:13AM -0800, Travis Scrimshaw wrote: >Hey Andrew, > It sounds more like you want to use a spare matrix (or even just a >dictionary with a tuple as the key) and fill in entries as you compute >them. A sparse matrix would probably not work, as you can't make difference between a coefficient that has been computed and is zero, and a not computed coefficient. I guess we need both; morphism implemented as matrices, and morphisms implemented as "lazy matrices", and we should share as much as possible between the two. Andrew: please keep up implementing such things! Don't worrying too much about the design; just make it as straightforward as possible. When the infrastructure will be in place, it should be easy to cleanup the things before getting them into Sage. Btw: Hom(F, G, C) models the set of all morphisms from F to G in the category C. By default, C is the meet of the categories of F and G. Of course, for most categories one can't do much with that. But there certainly are categories where we can or could and would want to: - Hom(V, W, VectorSpaces) - Hom(V, W, A-modules) - Hom(F, G, Groups) Cheers, Nicolas -- Nicolas M. Thiéry "Isil" 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-devel@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: Constructing homs
Hey Andrew, It sounds more like you want to use a spare matrix (or even just a dictionary with a tuple as the key) and fill in entries as you compute them. Best, Travis On Wednesday, December 5, 2012 3:29:27 AM UTC-8, Andrew Mathas wrote: > > > huh? >> sage: m=matrix([[1,2],[3,4]]) >> sage: m >> [1 2] >> [3 4] >> sage: m[1,1]=100 >> sage: m >> [ 1 2] >> [ 3 100] >> sage: >> > > Yes, you're right. My issue with matrices is that I can't write something > like: > > sage: matrix([[1,0],[None,0]]) > > (Unless, of course, you want to correct me again:) > > A. > > -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/bGhR-svWEI8J. To post to this group, send email to sage-combinat-devel@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: Constructing homs
> huh? > sage: m=matrix([[1,2],[3,4]]) > sage: m > [1 2] > [3 4] > sage: m[1,1]=100 > sage: m > [ 1 2] > [ 3 100] > sage: > Yes, you're right. My issue with matrices is that I can't write something like: sage: matrix([[1,0],[None,0]]) (Unless, of course, you want to correct me again:) A. -- You received this message because you are subscribed to the Google Groups "sage-combinat-devel" group. To view this discussion on the web visit https://groups.google.com/d/msg/sage-combinat-devel/-/6Qm7YHqf5g8J. To post to this group, send email to sage-combinat-devel@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: Constructing homs
On 2012-12-05, Andrew Mathas wrote: > --=_Part_1499_29645117.1354701799117 > Content-Type: text/plain; charset=ISO-8859-1 > > > >> - Matrices with rows and columns indexed by whatever objects >> > > I have a (very) rough prototype for this as it is one of the things that I > need. Rather than matrices, however, I am thinking of making the underlying > object just an array/table as for my applications the full matrix is often > not known and more entries are added as the calculations proceed whereas > matrices are immutable. huh? sage: m=matrix([[1,2],[3,4]]) sage: m [1 2] [3 4] sage: m[1,1]=100 sage: m [ 1 2] [ 3 100] sage: -- 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-devel@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.
