[R] Surprising Symbolic Model Formula Evaluations

Richard M. Heiberger rmh @end|ng |rom temp|e@edu
Fri Oct 11 19:58:58 CEST 2019


I can't duplicate your examples
This is what I see
> y ~ 1:x
y ~ 1:x

Please try again in a vanilla R session, and send a reproducible example.
vanilla means start R from the operating system command line with
R --vanilla

this prevents any of your initialization files from being loaded.  See
?Startup
for details.

On Fri, Oct 11, 2019 at 1:05 PM Emi Tanaka <dr.emi.tanaka using gmail.com> wrote:
>
> Hi,
>
> I'm wondering about some logics behind the following simplifications:
>
> y ~ 1:x simplifies to y ~ 1
> y ~ x:1 simplifies to y ~ 1
> y ~ x*1 simplifies to y ~ x
> y ~ 1*x simplifies to y ~ 1
>
> Mainly I would have expected y ~ 1:x to simplify to y ~ x and the cross
> operator to be invariant to order.
>
> I have some further surprising cases below that I'd also like to know more
> about but just above will also be great.
>
> https://rpubs.com/emitanaka/unexpected-formula-eval
>
> Best,
>
> Emi
>
> *Dr. Emi Tanaka* | Lecturer in Statistics
>
> Faculty of Science, School of Mathematics and Statistics
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