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.
> >
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