Are you a contributor or core dev on one of those packages? That would be
useful context to have.
Also, did you see Jim Baker's module? How do you propose to translate
Patsy's ':' operator?
On Sun, Feb 23, 2020 at 5:22 PM Aaron Hall via Python-ideas <
python-ideas@python.org> wrote:
> > Is there an existing function in one of the libraries you mention
> > that has the desired behavior (in the context of that library)? That
> would
> > help.
>
> Yes, and we are currently parsing and evaluating strings to convey the
> meaning.
>
> Patsy is currently used by statsmodels to parse strings in the following
> way:
>
> ```
> from patsy import ModelDesc, Term, EvalFactor
> ModelDesc([Term([EvalFactor("y")])],
> [Term([]),
> Term([EvalFactor("a")]),
> Term([EvalFactor("a"), EvalFactor("b")]),
> Term([EvalFactor("np.log(x)")])
> ])
> ```
> "Compare to what you get from parsing the above formula:"
>
> ```
> ModelDesc.from_formula("y ~ a + a:b + np.log(x)")
> ```
>
> In the past when we have been eval'ing strings, we added functionality so
> users could avoid it (`getattr`, et. al.).
>
> Sympy is rather new, but I think they'd appreciate it since they have an
> entire subpackage for distributions:
>
> https://docs.sympy.org/latest/modules/stats.html
>
> I do envision other usages, but these are the strongest cases I have right
> now.
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