[R] Surprising Symbolic Model Formula Evaluations
wdun|@p @end|ng |rom t|bco@com
Fri Oct 11 20:17:15 CEST 2019
Look at what terms() (hence lm()) does with such formulae:
Classes 'terms', 'formula' language y ~ 1 * x
..- attr(*, "variables")= language list(y, x)
..- attr(*, "factors")= int(0)
..- attr(*, "term.labels")= chr(0)
..- attr(*, "order")= int(0)
..- attr(*, "intercept")= int 1
..- attr(*, "response")= int 1
..- attr(*, ".Environment")=<environment: R_GlobalEnv>
> coef(lm(y~1*x, data=data.frame(y=1:10,x=log2(1:10))))
On Fri, Oct 11, 2019 at 10:59 AM Richard M. Heiberger <rmh using temple.edu>
> 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
> for details.
> On Fri, Oct 11, 2019 at 1:05 PM Emi Tanaka <dr.emi.tanaka using gmail.com>
> > 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
> > 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
> > <
> > Social Media Coordinator, Central, International Biometrics Society
> > <https://twitter.com/IBSstats>
> > *THE UNIVERSITY OF SYDNEY*
> > 827, Carslaw F07 | The University of Sydney | NSW | 2006
> > *Phone:* +61 2 9351 3039
> > *Website:* * <http://sydney.edu.au/>*https://emitanaka.github.io/
> > *Twitter: *@statsgen
> > CRICOS 00026A
> > This email plus any attachments to it are confidential.
> > Any unauthorised use is strictly prohibited. If you receive this email in
> > error, please delete it and any attachments. Please think of our
> > environment and only print this e-mail if necessary.
> > [[alternative HTML version deleted]]
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > and provide commented, minimal, self-contained, reproducible code.
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> PLEASE do read the posting guide
> and provide commented, minimal, self-contained, reproducible code.
[[alternative HTML version deleted]]
More information about the R-help