Supporting ~ as a binary operator is an interesting idea, especially given the relatively limited usage of unary ~. However, the big hole in this proposal for formulas is that there is a de facto standard "minilanguage" for writing such formulas in Python, namely what Patsy supports: https://patsy.readthedocs.io/en/latest/formulas.html Patsy is used by statsmodels and other tools to support the same formulas as we see in R (or S).
We immediately see the problem with the interaction operator : (colon), which conflicts with how it is used to support annotations in Python. Given that this formula minilanguage is comprehensive, this seems to be a fatal objection. Note that deferred evaluation is sort of a red herring - it is straightforward to defer execution in Python's object model, as we see in SymPy, Pandas dataframes where clauses, and SQLAlchemy, among other examples. On Sun, Feb 23, 2020 at 5:37 PM <jdve...@gmail.com> wrote: > Aaron Hall wrote: > > Currently, Python only has ~ (tilde) in the context of a unary operation > (like > > -, with __neg__(self), and +, __pos__(self)). > > ~ currently calls __invert__(self) in the unary context. > > I think it would be awesome to have in the language, as it would allow > modelling along the > > lines of R that we currently only get with text, e.g.: > > smf.ols(formula='Lottery ~ Literacy + Wealth + Region', data=df) > > With a binary context for ~, we could write the above string as pure > Python, with > > implications for symbolic evaluation (with SymPy) and statistical > modelling (such as with > > sklearn or statsmodels) - and other use-cases/DSLs. > > In LaTeX we call this \sim (Wikipedia indicates this is for "similar > to"). > > I'm not too particular, but __sim__(self, other) would have the benefits > of > > being both short and consistent with LaTeX. > > This is not a fully baked idea, perhaps there's a good reason we haven't > added a binary > > ~. It seems like I've seen discussion in the past. But I couldn't find > such > > discussion. And as I'm currently taking some statistics courses, I'm > getting > > R-feature-envy again... > > What do you think? > > Aaron Hall > > I really do not fully understand your proposal. I do not know nothing > about R and my statistical knowledge has gone long ago. > > However, I think that we cannot expect that Python accommodates every > existing domain. Let me explain: Python have not special features, syntax, > operators to deal with SQL, HTML, ini files, OpenGL, etc. These domains, > and others, are supported via libraries, outside of the language core. > > ~ exists in bit-wise context and, as long as I know, it comes from C --I > have never used it indeed in Python. It is a unary operator because it > works in that way as a bitwise operator. > > I cannot see any improvement in becoming ~ into a binary operator. I > imagine that a binary ~ would have a completely different meaning from a > unary ~. I can foresee many problems here. > > In my opinion, you should prove that binary ~ has a relevant benefit for > the whole language, not just for R tasks. It should be useful in some > different domains and behave consistently --or at least so consistent as > possible-- in those domains. > > Can you, for instance, envision other uses of binary ~ beyond R? > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/UMXBIM6TSOTR76KOBOJXGVJUDMX7IHBT/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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