The situation is the one in which I get a sympy expression out of a function that ends in `return my_polynomial_inRn` and now I want to pass this to another function (e.g. to make plots or whatever) without having to know the names of the symbols involved, which is exactly what free_symbols does for me in this instance. Do you see another way around this?
On Fri, Jul 10, 2020 at 11:08 AM Oscar Benjamin <oscar.j.benja...@gmail.com> wrote: > Hi Roberto, > > I already answered this on SO: > > https://stackoverflow.com/questions/62798213/keep-the-order-of-parameters-fixed-in-sympy-lambdify-from-free-symbols/62800716?noredirect=1#comment111075099_62800716 > > If you are using symarray to generate the symbols then you can get the > list of symbols from the symarray directly and then pass those to > lambdify. > > I can't think of any situation where it would be a good idea to use > free_symbols to get the arguments to lambdify. > > Oscar > > On Fri, 10 Jul 2020 at 08:10, roberto franceschini > <franceschini.robe...@gmail.com> wrote: > > > > Hello, I have opened an issue for the input of lambdify. If you want to > disallow sets as inputs I think it is fair. However, It would be nice to > have that free_symbol can be given directly as input for lambdify, is that > possible? should I use something else than free_symbols for this purpose? > > > > On Thu, Jul 9, 2020 at 9:55 PM Aaron Meurer <asmeu...@gmail.com> wrote: > >> > >> Can you open an issue in the issue tracker for this? I agree that sets > >> should not be allowed. > >> > >> Aaron Meurer > >> > >> On Thu, Jul 9, 2020 at 3:08 AM Roberto <franceschini.robe...@gmail.com> > wrote: > >> > > >> > I have seen that lambdify wants a list for the arguments to be > treated as symbols. This list can be also give as a python set, e.g. {x,y,z > }, which is exactly what would be returned by a .free_symbol property. If > lambdify is feed a set like that of the output of .free_symbol it may > change their order in the conversion from set to list. This is done > silently and may cause major disfunction in the use of the lamdified > function because you think x is x, but is y instead and so on. > >> > I would like to ask developers to check for the type of the lambdify > list of arguments and throw a warning to flag that a set is being converted > and that the ordering is not guaranteed. > >> > Given that .free_symbols returns a set, not a list, this is very > common pitfall in my opinion and must be prevented. > >> > > >> > -- > >> > 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 sympy+unsubscr...@googlegroups.com. > >> > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/c1517b79-490b-4a1b-b526-3e3842b55fbco%40googlegroups.com > . > >> > >> -- > >> 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 sympy+unsubscr...@googlegroups.com. > >> To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAKgW%3D6KuqnjJHTObyDxK0tvaF_Frxzd-MfyQSY94v-oTUWyNAg%40mail.gmail.com > . > > > > -- > > 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 sympy+unsubscr...@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAJxM9JqSoqQQkYH9UUXGyXNqRtY9VHJxKByc8Fv8%2BPaqFudP6w%40mail.gmail.com > . > > -- > 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 sympy+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAHVvXxSsngVE_X-aBRYWER5sESZW-e-EnjwWcfGAhM%3D%2Beq97zQ%40mail.gmail.com > . > -- 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 sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAJxM9Jpza%3DgRk9%3DZ2_thBS4xN_dkjCaB5PTMcz1hj8wHG_R90g%40mail.gmail.com.
