[R] Surprising Symbolic Model Formula Evaluations

[Emi Tanaka]

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


Secretary, NSW Branch, Statistical Society of Australia
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