If you know the ordering is total (i.e., for any two expressions one is greater than the other in your given domain), you could just evaluate at some value in (0, 1) and sort by that.
By the way, how general are your expressions? Do they have symbolic constants (more than one symbol)? Are they always polynomials or rational functions? Aaron Meurer On Oct 15, 2013, at 6:08 PM, BR <[email protected]> wrote: Unfortunately, the example is just a basic case of the functionality I'd want to use - I need a reliable way of sorting symbolic values like that. Other software I've tried struggles with this a lot, so I thought SymPy would work better - unfortunately not! Thank you for your reply anyway. On Wednesday, 16 October 2013 00:45:38 UTC+1, Aaron Meurer wrote: > > I think the logic you want isn't implemented. Right now, the > assumptions module doesn't really do anything with interval type > assumptions, like 0 < x < 1. It only knows about assumptions like > positive or negative. > > Of course, if all you want to do is sort symbols by their exponent, > that is not too difficult to do, especially if you know for sure that > each element of your list is a power of that symbol. You just need to > define an appropriate key function and use it when sorting. > > Aaron Meurer > > On Tue, Oct 15, 2013 at 3:47 PM, BR <[email protected] <javascript:>> > wrote: > > Hey, > > > > I've been trying to find some information online on SymPy's assumptions > > module and unfortunately I can't find an answer to my question. Is it > > possible to declare symbols with assumptions in such a way that they are > > respected when sorting them? For instance, is it possible to declare a > > symbol x with the assumption that 0<x<1, so that sorting [w, w**2, w**3] > > gives [w**3, w**2, w]? > > > > Thanks. > > > > -- > > You received this message because you are subscribed to the Google > Groups > > "sympy" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to [email protected] <javascript:>. > > To post to this group, send email to [email protected]<javascript:>. > > > Visit this group at http://groups.google.com/group/sympy. > > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
